ASTM E2026-16a

Standard Guide for Seismic Risk Assessment of Buildings

ABSTRACT
This guide provides guidance on conducting seismic risk assessments for buildings. As such, this guide assists a User to assess a property’s potential for losses from earthquake occurrences. Hazards addressed in this guide include earthquake ground shaking, earthquake-caused site instability, including fault rupture, landslides and soil liquefaction, lateral spreading and settlement, and earthquake-caused off-site response impacting the property, including flooding from dam or dike failure, tsunamis and seiches. This guide is intended to reflect a commercially prudent and reasonable investigation for performance of seismic risk assessments. Seismic risk assessments may be performed for an individual building or a group of buildings. This guide provides suggested approaches for the performance of five different types of seismic risk assessments. Building stability, site stability, building damageability, contents damageability, business interruption, and application and temporal relevance of report. Each is intended to serve different financial and management needs of the User. An earthquake ground motion assessment should be conducted in conjuction with probable loss evaluations for building damageability and may have applications in some scenario loss studies, as well as building stability or site stability assessments. Seismic risk assessments may consider varying degrees of assessment of a building or buildings from Level 0 to Level 3.
SIGNIFICANCE AND USE
4.1 Uses—This Guide is intended for use on a voluntary basis by parties such as lenders, loan servicers, insurers and equity investors in real estate (Users) who wish to estimate possible earthquake losses to buildings. This guide outlines procedures for conducting a seismic risk assessment for a specific User considering the User's requirements for due diligence. The specific purpose of this guide is to provide Users with seismic risk assessment during the anticipated term for holding either the mortgage or the deed. A seismic risk assessment prepared in accordance with this guide should reference or state that the guidance in this document was used as a basis for the report and should also identify any deviations from the guidelines. This guide is intended to reflect a commercially prudent and reasonable investigation for performance of seismic risk assessments.  
4.1.1 Users—This Guide is designed to assist the User in developing information about the earthquake-related damage potential of a building, or groups of buildings.
4.1.1.1 Use of this guide may permit a User to satisfy, in part, their requirements for due diligence in assessing a building’s potential for losses associated with earthquakes for real estate transactions.  
4.1.2 Types of Investigations—This guide provides suggested approaches for the performance of five different types of assessments. Each is intended to serve different financial and management needs of the User. Several of these types of assessment specifically depend on characterization of the earthquake ground motion as given in Section 7.
4.1.2.1 Building Stability (BS)—Assessment of whether the building will maintain vertical load-carrying capacity in whole or in part during considered earthquake ground motions (see Section 8).
4.1.2.2 Site Stability (SS)—Assessment of the likelihood that the site will remain stable in earthquakes and is not subject to failure through faulting, soil liquefaction, landslide, or other site respo...
SCOPE
1.1 This guide provides guidance on conducting seismic risk assessments for buildings. As such, this guide assists a User to assess a property's potential for losses from earthquake occurrences.  
1.1.1 Hazards addressed in this guide include:
1.1.1.1 Earthquake ground shaking,
1.1.1.2 Earthquake-caused site instability, including fault rupture, landslides, soil liquefaction, lateral spreading and settlement, and
1.1.1.3 Earthquake-caused off-site response impacting ...

General Information

• Status: Published
• Publication Date: 14-May-2016
• ICS: 91.120.25 - Seismic and vibration protection
• Technical Committee: E06 - Performance of Buildings
• Drafting Committee: E06.25 - Whole Buildings and Facilities

Relations

• Replaces: ASTM E2026-16 - Standard Guide for Seismic Risk Assessment of Buildings
• Effective Date: 15-May-2016
• Refers: ASTM E631-15 - Standard Terminology of Building Constructions
• Effective Date: 01-Mar-2015
• Refers: ASTM E631-14 - Standard Terminology of Building Constructions
• Effective Date: 01-Nov-2014
• Refers: ASTM E631-06 - Standard Terminology of Building Constructions
• Effective Date: 01-Jun-2006
• Refers: ASTM E631-93a(1998)e1 - Standard Terminology of Building Constructions
• Effective Date: 28-Jul-2000
• Referred By: ASTM E2557-16a - Standard Practice for Probable Maximum Loss (PML) Evaluations for Earthquake Due-Diligence Assessments<rangeref></rangeref >
• Effective Date: 15-May-2016

Overview

ASTM E2026-16a: Standard Guide for Seismic Risk Assessment of Buildings is a critical ASTM International standard that outlines best practices for evaluating earthquake-related risks impacting existing buildings. The guide is widely adopted by professionals in real estate, insurance, lending, and risk management sectors to estimate a property's potential for seismic losses. By addressing hazards such as earthquake ground shaking, site instability, fault rupture, landslides, soil liquefaction, lateral spreading, and consequences from events like tsunamis or off-site flooding, ASTM E2026-16a enables users to perform commercially prudent and reasonable seismic investigations.

This standard promotes a consistent, transparent approach for assessing seismic risk for individual buildings or clusters of structures. It recommends different levels and types of investigation based on user needs, regulatory requirements, financial considerations, and property-specific factors.

Key Topics

• Seismic Hazards Covered:

  • Earthquake ground shaking
  • Site instability (fault rupture, landslides, soil liquefaction, settlement, lateral spreading)
  • Earthquake-induced off-site impacts (flooding due to dam/dike failure, tsunamis, seiches)

• Assessment Types:
  ASTM E2026-16a outlines five main types of seismic risk assessments, each tailored to different user needs:

  • Building Stability (BS): Evaluates the ability of a structure to retain its vertical load-carrying capacity during earthquakes.
  • Site Stability (SS): Assesses likelihood of site failure due to ground-related hazards.
  • Building Damageability (BD): Estimates the degree and cost of building damage.
  • Contents Damageability (CD): Considers potential loss or damage to non-structural contents.
  • Business Interruption (BI): Evaluates downtime and loss of function due to earthquake impacts.

• Assessment Levels:

  • Level 0 to Level 3, allowing customization from basic screening to detailed engineering evaluations based on available data, purpose, and risk tolerance.

• Probable Loss (PL) and Scenario Loss (SL):

  • Supports both probabilistic and scenario-based approaches to estimate potential losses.

• Due Diligence and User Focus:

  • Offers actionable guidance for lenders, insurers, equity investors, and real estate managers on fulfilling due diligence during transactions.

Applications

• Commercial Real Estate Transactions:
  Lenders, loan servicers, and investors utilize ASTM E2026-16a to estimate probable maximum loss and scenario loss when conducting property due diligence before acquisitions, refinancing, or developing risk mitigation strategies.

• Insurance Underwriting:
  Insurers and reinsurers use the guide to quantify potential earthquake-related exposures for underwriting and portfolio management.

• Risk Management:
  Property owners and managers conduct seismic risk assessments to prioritize retrofits, evaluate emergency preparedness, and ensure business continuity.

• Regulatory and Code Compliance:
  Helps stakeholders align property assessments with due diligence requirements and supports compliance with local building codes and international risk assessment standards.

Related Standards

• ASTM E631: Terminology of Building Constructions - offers definitions critical to understanding seismic and building assessment terms.
• ASCE 7: Minimum Design Loads for Buildings and Other Structures - recognized guidance on design loads, including those from seismic events.
• ASCE 31 & ASCE 41: Standards for seismic evaluation and retrofit of existing buildings.
• ICC IBC: International Building Code - referenced for current construction requirements and seismic considerations.

ASTM E2026-16a serves as an essential reference for anyone involved in the seismic risk assessment of buildings, enabling a standardized, systematic approach for evaluating and reporting on seismic hazards. Implementing this guide helps reduce uncertainties, supports prudent investment and lending decisions, and ultimately contributes to safer, more resilient buildings in earthquake-prone regions.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2026 − 16a
Standard Guide for
Seismic Risk Assessment of Buildings
This standard is issued under the fixed designation E2026; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Lenders, insurers, and equity owners in real estate are giving more intense scrutiny to earthquake
riskthaneverbefore.The1989LomaPrieta,Californiaearthquake,whichcausedmorethan$6billion
in damage, accelerated the trend toward considering loss estimation in real estate transactions. The
1994 Northridge, California earthquake, with over $20 billion in damage, made seismic risk
assessment an integral part of real estate financial decision-making for regions at risk of damaging
earthquakes. Users of Seismic Risk Assessment reports need specific and consistent measures for
assessing the possibility of future loss due to earthquake occurrences. This guide discusses specific
approaches that the real estate and technical communities can consider a basis for characterizing the
seismic risk assessment of buildings in an earthquake. It uses two concepts to characterize earthquake
loss: probable loss (PL) and scenario loss (SL). Use of the term probable maximum loss (PML) is
acceptable, provided it is specifically and adequately defined by the User.
1. Scope Providers who prepared the report and those who would like to
use such prior reports.
1.1 This guide provides guidance on conducting seismic
1.1.2.6 Contractual and legal obligations between a Pro-
risk assessments for buildings. As such, this guide assists a
Usertoassessaproperty’spotentialforlossesfromearthquake vider and a User, and other parties, if any.
occurrences.
1.1.3 It is the responsibility of the User of this guide to
1.1.1 Hazards addressed in this guide include:
establish appropriate life safety and damage prevention prac-
1.1.1.1 Earthquake ground shaking,
tices and determine the applicability of current regulatory
1.1.1.2 Earthquake-caused site instability, including fault
limitations prior to use.
rupture, landslides, soil liquefaction, lateral spreading and
1.2 The objectives of this guide are:
settlement, and
1.1.1.3 Earthquake-caused off-site response impacting the
1.2.1 To synthesize and document guidelines for seismic
property,includingfloodingfromdamordikefailure,tsunamis
risk assessment of buildings;
and seiches.
1.2.2 To encourage standardized seismic risk assessments;
1.1.2 This guide does not address the following:
1.2.3 To establish guidelines for field observations of the
1.1.2.1 Earthquake-causedfiresandtoxicmaterialsreleases.
site and physical conditions, and the document review and
1.1.2.2 Federal, state, or local laws and regulations of
research considered appropriate, practical, sufficient, and rea-
building construction or maintenance. Users are cautioned that
sonable for seismic risk assessment;
current federal, state, and local laws and regulations may differ
1.2.4 To establish guidelines on what reasonably can be
from those in effect at the time of the original construction of
expected of and delivered by a Provider in conducting the
the building(s).
1.1.2.3 Preservation of life safety. seismic risk assessment of buildings; and
1.1.2.4 Prevention of building damage.
1.2.5 To establish guidelines by which a Provider can
1.1.2.5 Contractual and legal obligations between prior and
communicate to the User observations, opinions, and conclu-
subsequentUsersofseismicriskassessmentreportsorbetween
sions in a manner that is meaningful and not misleading either
by content or by omission.
This guide is under the jurisdiction of ASTM Committee E06 on Performance
of Buildings and is the direct responsibility of Subcommittee E06.25 on Whole 1.3 The values stated in inch-pound units are to be regarded
Buildings and Facilities.
as standard. The values given in parentheses are mathematical
Current edition approved May 15, 2016. Published June 2016. Originally
conversions to SI units that are provided for information only
approved in 1999. Last previous edition approved in 2016 as E2026-16. DOI:
10.1520/E2026-16A. and are not considered standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2026 − 16a
2. Referenced Documents ventilating and air conditioning equipment, ducts, control
2 systems etc; plumbing systems include domestic water heaters,
2.1 ASTM Standards:
piping, controls, plumbing fixtures, waste water system piping
E631 Terminology of Building Constructions
and natural gas or propane systems, storm water drains and
2.2 ICC Standard:
pumps etc; electrical systems include switchgear, transformers,
IBC International Building Code, current edition
breakers, wiring, lighting fixtures, emergency power systems
2.3 Other References—The following resource documents
etc; and fire life-safety systems include fire sprinkler systems,
provide technical guidance for the seismic evaluation and
monitoring and alarm systems etc. Not included in building
retrofit of existing buildings:
systems are those contained within a building and defined as
ASCE7-10 MinimumDesignLoadsforBuildingsandOther
contents.
Structures
3.2.4 business interruption, n—a period of interruption to
ASCE 31 Seismic Evaluation of Existing Buildings
normal business operations that can potentially or materially
ASCE 41-13 Seismic Evaluation and Retrofit of Existing
cause a loss to the owner/operator of that business through loss
Buildings
of use of the building until use is restored consistent with
business operations.
3. Terminology
3.2.4.1 Discussion—The loss may be partial or total for the
3.1 Definitions:
period under consideration. Business interruption is expressed
3.1.1 See Terminology E631.
in days/weeks/months of downtime for the building as a whole
3.1.2 For definition of terms related to building
or the equivalent operating value.
construction, ASCE 31 and ASCE 41 provide additional
resources for understanding terminology and language related 3.2.5 construction documents, n—documents used in the
initial construction phase and any subsequent modification(s)
to seismic performance of buildings.
of building(s) for which the seismic risk assessment is pre-
3.1.3 For definition of terms and additional detailed infor-
pared. Construction documents include drawings, calculations,
mation on concepts related to seismic events and structural
specifications, geotechnical reports, construction reports, and
design, see references at the end of this document.
testing results.
3.2 Definitions of Terms Specific to This Standard—This
3.2.5.1 Discussion—Generally as-built plans are the pre-
section provides definitions of concepts and terms specific to
ferred form of construction documents.
this guide. The concepts and terms are an integral part of this
3.2.6 contents, n—elements contained within the building
guide and are critical to an understanding of this guide and its
that are not defined as building systems.
use.
3.2.6.1 Discussion—Examples include tenant-installed
3.2.1 active earthquake fault, n—an earthquake fault that
equipment, storage racks, material handling systems, shelving,
has exhibited surface displacement within Holocene time
stored inventories, furniture, fixtures, office machines, com-
typically about the last 11 000 years.
puter equipment, filing cabinets, and personal property.
3.2.2 building code, n—a collection of laws (regulations,
ordinances, or statutory requirements) applicable to buildings, 3.2.7 correlation, n—the tendency or likelihood of the
behavior of one element to be influenced by the known
adopted by governmental (legislative) authority and adminis-
teredwiththeprimaryintentofprotectingpublichealth,safety, behavior of another element.
and welfare.
3.2.8 damage or repair cost, n—cost required to restore the
3.2.3 building systems, n—all physical systems that com- building to its pre-earthquake condition, allowing for salvage
prise a building and its services.
and demolition.
3.2.3.1 Discussion—This includes architectural, structural, 3.2.8.1 Discussion—The value includes hard costs of con-
mechanical, plumbing, electrical, fire life-safety, vertical trans-
struction as well as soft costs for design, site supervision,
portation and security systems. More specifically architectural management, etc. (See also replacement cost.)
systems include non-structural building envelopes, roofing,
3.2.9 damage ratio, n—ratio of the damage or repair cost
ceilings, partitions, non-structural demising walls etc; struc-
divided by the replacement cost.
tural systems include both gravity and seismic force-resisting
3.2.10 dangerous conditions, n—situationsthatposeathreat
systems and foundations; mechanical systems include heating,
or possible injury to the occupants or adjacent area consistent
with IBC definition.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.11 deficiency, n—conspicuous defect(s) in the building
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
or significant deferred maintenance items of a building and its
Standards volume information, refer to the standard’s Document Summary page on
components or equipment.
the ASTM website.
Available from International Code Council (ICC), 500 New Jersey Ave., NW,
3.2.11.1 Discussion—Conditions resulting from the lack of
6th Floor, Washington, DC 20001, http://www.iccsafe.org.
routine maintenance, miscellaneous repairs, operating
Available from American Society of Civil Engineers (ASCE), 1801 Alexander
maintenance, etc. are not considered a deficiency.
Bell Dr., Reston, VA 20191, http://www.asce.org.
The successor of FEMA 310 issued as a standard in 2003, with periodic
3.2.12 demand surge, n—a temporary economic condition
revisions.
following a large or great earthquake in which the increased
The successor of FEMA 356 issued as a standard in 2006, with periodic
revisions. demand for materials, labor, and services results in an increase
E2026 − 16a
in the cost and time to repair damage to buildings compared to 3.2.18 field assessor, n—the person assigned by the Senior
the cost and time to repair the same damage under normal Assessor who conducts the site visits of the property to
conditions or following smaller earthquakes. observe, evaluate, and document the lateral load-resisting
system. Other qualified persons may assist the Field Assessor.
3.2.12.1 Discussion—The phenomenon results from a com-
See 6.2.3 for qualifications required to perform such functions
plex time-dependent process of supply and demand. Objective
for Level 1 or higher assessments.
and complete datasets for demand surge for large to great
3.2.19 independent reviewer, n—independent technically
earthquakes in the United States are unavailable, as are
qualified individual or organization that has not been engaged
peer-reviewed public models to reliably predict the effects of
in the design or modifications of the building(s), and is not in
demand surge.
any way affiliated with the Provider.
3.2.13 design basis earthquake (DBE), n—the site ground
motion with a 10 % probability of exceedance in 50 years, 3.2.19.1 Discussion—The concept may also be represented
equivalent to a 475-year return period for exceedance, or a by the phrase “Independent Peer Reviewer.” Independent
0.2105 % annual probability of occurrence. Review is conducted during the seismic risk assessment (and
3.2.13.1 Discussion—The design basis earthquake ground
typically involves interaction with the Provider) rather than
motions are associated with any earthquake that has the after the completion of the seismic risk assessment by a Third
specified site ground motion value; often there are several
Party Reviewer. See 6.4 and 6.5.
earthquakes with different magnitudes and causative faults that
3.2.20 interdependency, n—a condition wherein the func-
yield equivalent site peak ground motions.
tion of the building is dependent on another building, on
3.2.14 distribution function, n—the probability distribution
utilities, or on other critical elements in the supply chain.
for a random variable.
3.2.20.1 Discussion—Other critical elements include trans-
3.2.14.1 Discussion—The random variable may include
portation and may include a customer, vendor (for example,
such things as loss, ground motion, or other consequence of
supplier of materials), contractor (supplier of services), staff
7,8,9
earthquake occurrence.
(for example, supplier of staff), information (for example, data
3.2.15 due diligence, n—the assessment of the condition of
processing for accounting or distribution), etc.
a property for the purposes of identifying conditions or
3.2.21 landslide, n—(1) ground motion, the rapid
characteristics of the property, including potentially dangerous
downslope movement of soil or rock material, or both, often
conditions, that may be important to determining the appropri-
lubricated by ground water, over a basal shear zone; and (2)
ateness of the property for financial or real estate transactions.
geological, stationary material deposited in the past by the
3.2.15.1 Discussion—The extent of due diligence exercised
rapid downslope movement of soil or rock material, or both.
onbehalfofaUserisusuallyrelatedtotheUser’stolerancefor
3.2.22 lateral load-resisting system, n—the elements of the
uncertainty, the purpose of seismic risk assessment, the re-
structural system that provide support and stability to the
sources and time available to the Provider to conduct the site
building under seismic and wind forces.
visit and review construction documents.
3.2.16 expected value, n—of a random variable,theaverage 3.2.23 magnitude of earthquake, n—any of a variety of
or mean of the distribution function. measures that indicates the “size” or “energy release” of an
3.2.16.1 Discussion—The expected value is determined as earthquake.
the sum (or integral) of all the values that can occur multiplied
3.2.23.1 Discussion—At least 20 different magnitude scales
by the probability of their occurrence. (Compare: median
areinusewithinthetechnicalcommunity.Themostcommonly
value.)
usedlaytermistheRichtermagnitude,whichisdeterminedby
taking the common logarithm (base 10) of the largest ground
3.2.17 fault zone, n—area within a prescribed distance from
motion recorded during the arrival of a “P” wave, or seismic
any of the surface traces of a fault.
surface wave, and applying a standard correction for the
3.2.17.1 Discussion—The distance depends on the magni-
distance to the epicenter of the earthquake. The measure most
tude of earthquakes that could occur on the fault—typically
widely used in the technical community is the moment
500 ft (152 m) from major faults, which are those capable of
magnitude, a measure of the total strain energy released in the
earthquakes with magnitudes of 6.5 or greater, and 250 ft
event. Magnitudes calculated using different scales can vary
(761 m) away from other well-defined faults. Within
widely for the same earthquake.
California, the fault zones are determined by the California
GeologicalSurveyundertheEarthquakeSpecialStudiesZones
3.2.24 maximum capable earthquake (MCE), n—earthquake
Act for active and potentially active faults that have been
that can occur within the region that produces the largest
identified by the state or other governmental bodies.
average ground motion at the site of interest.
3.2.24.1 Discussion—This is NOT the same as the ASCE 7
7 definition of risk-targeted maximum considered earthquake
Earthquake Damage Evaluation Data for California, Report ATC-13, Applied
(MCE ), or past definitions of maximum considered earth-
Technology Council, Redwood City, CA, 1985. ATC-13-1 issued in 2003.
R
Thiel, C. C., and Zsutty, T. C., “Earthquake Characteristics and Damage
quake (MCE) as found inASCE 7 orASCE 41.The concept of
Statistics,” Earthquake Spectra, Earthquake Engineering Research Institute,
maximum capable earthquake (MCE) for purposes of the
Oakland, CA, Vol 3, No. 4, November 1987.
Guide is a deterministic event, and does not include a return
Richter, C. F., Elementary Seismology, W.H. Freeman, San Francisco, CA,
1958. period value.
E2026 − 16a
3.2.25 median value, n—value that divides the distribution 3.2.35 potentially active fault, n—a fault that shows evi-
function into equal parts, such that the value of the random dence of surface displacement during the Quaternary period
(approximately the last two million years).
variable has an equal probability of being above or below the
reference value. (Compare expected value.) 3.2.35.1 Discussion—This is the definition used in Earth-
quake Fault Zones (previously referred to as Alquist-Priolo
3.2.26 Modified Mercalli Intensity (MMI), n—qualitative
Special Study Zones) in California. Other definitions may be
description of the local effects of the earthquake at a site.
appropriateindifferentseismichazardregions.Thepointofthe
3.2.26.1 Discussion—Normally, MMI is given as a roman
definition is to preclude concern for faults that have not moved
numeral, from I to XII, to emphasize its qualitative, not
in a very long time; that is, much longer time periods, such as
quantitative, nature. A single earthquake can have many
thosethatdominatetheEasternandMidwesternportionsofthe
different MMI intensities assigned over the region in which the
United States.
earthquake is felt. Use of MMI to characterize ground motions
3.2.36 probabilistic ground motion, n—earthquake ground
for use in the seismic risk assessment of buildings should be
motions for the building site that are determined from an
done with caution because the damage level predicted is
evaluation of the seismic exposure for the site for a given time
associated with a very wide range of earthquake ground
period and are represented by a probability distribution func-
motions, not a specific earthquake ground motion.
tion.Whereappropriate,thegroundmotionassessmentprocess
3.2.27 non-structural components, n—components of a
should reflect conditional probabilities of the temporal depen-
building system that are not part of the vertical or lateral-load dence of earthquakes on specific seismic features, where they
are known.
resisting structural systems nor are defined as contents.
3.2.37 probable loss (PL), n—earthquake loss to the build-
3.2.28 observations, n—the relevant information or
ing systems that has a specified probability of being exceeded
measurements, or combination thereof, documented during the
in a given time period, or an earthquake loss that has a
site visit survey.
specified return period for exceedance.
3.2.29 obvious, adj—readily accessible and can be seen
3.2.37.1 Discussion—This value is meant to reflect in a
easily by the Provider without the aid of any instrument or
statistically consistent computational manner all of the uncer-
device during a site visit.
tainties that can impact damage, including when and where
earthquakes occur and with what magnitude, attenuations of
3.2.30 occupant, n—of a building, an individual or
ground motion to the site, local site effects and performance of
individuals, who is or will be occupying space in a particular
the building systems in this ground motion. The PL is ex-
building(s) under study, or a part thereof.
pressed in terms of the damage ratio and is generally limited to
3.2.30.1 Discussion—Persons who are authorized to be
earthquake loss associated with the earthquake ground-shaking
present only temporarily, or in special circumstances such as
hazard, but may include losses from other earthquake hazards
those permitted to pass through during an emergency, are
as prescribed by a User. Dollar values can be determined by
visitors.
multiplying the damage ratio by the replacement cost estimate
3.2.31 other earthquake hazards, n—other earthquake haz-
for the building. Where seismic analysis of discounted present
ards include, but are not limited to, soil liquefaction; ground
value is to be performed then annual PL, mean and standard
deformation including subsidence, rupture, differential
deviation are appropriate damageability measures for use in
settlement, landsliding, slumping, etc; and, hazards from off-
such application.
site response to the earthquake including flooding from dam or
3.2.38 probable maximum loss (PML), n—term historically
dike failure, tsunami, or seiche.
used to characterize building damageability in earthquakes.
3.2.32 owner, n—theentityorindividualholdingthedeedto
3.2.38.1 Discussion—PMLhas had a number of very differ-
the building, or their designated representative. An agent or
ent explicit and implicit definitions. The concepts of probable
contractormaybeconsideredanownerinsomecircumstances.
loss (PL) and scenario loss (SL) are used in this guide to
characterize the earthquake losses of an individual building or
3.2.33 P-delta effect, n—the secondary effect of column
groups of buildings. When a Provider uses the term PML, it
axialloadsandlateraldeflectionsontheshearsandmomentsin
should be defined in terms of SL or PL as defined herein.
various components of a building.
3.2.39 provider, n—person or organization that prepares a
3.2.34 peak ground acceleration, (PGA), n—the maximum
report and is responsible for the findings of the seismic risk
acceleration at a site caused by an earthquake ground motion.
assessment of a building or group of buildings.
PGA may be an actual recording or an estimate. PGA is most
3.2.40 replacement cost, n—cost required to construct an
often given as the maximum of the horizontal components and
entirely new building of the same size, envelope, configuration
is usually expressed as a fraction of gravitational acceleration,
2 2
andcharacterasthereferencedbuilding,assumingavirginsite.
g, 32.2 ft/s (9.8 m/s ). The terms effective peak acceleration
3.2.40.1 Discussion—Replacement cost includes costs for
(EPA) and/or effective maximum acceleration (EMA) are
construction, including building materials and labor; design;
sometimes used in seismic analysis. Where EPAand EMAare
site supervision; management; etc.
used, the basis for determination and justification of use should
be provided, including verification that the use requires this 3.2.41 retrofit scheme, n—preliminary suggestion(s) of
representation of ground motion as distinct from others. modifications or additions to the building intended to correct,
E2026 − 16a
mitigate, or repair a physical deficiency that will improve the provide on-site ladders, if available, and to provide safe access
seismic performance of the building so that it is acceptable to to all parts of the structure, including the roof. This definition
the User. implies that such a visit is preliminary, not in-depth, and
typically done without the aid of exploratory probing, removal
3.2.42 return period, n—of a random variable,istheinverse
of materials, or testing. It is literally the Provider’s (Field
of the annual probability that the value is equaled or exceeded.
Assessor’s) visual survey of the building(s) and site improve-
3.2.42.1 Discussion—Return period is not the time period
ments.
between occurrences of the value, but is the long-term average
of the random times between occurrences. Often, return period 3.2.50 soil liquefaction, n—the transformation of loose,
saturated, sandy soil materials into a fluid-like state.
is incorrectly interpreted to mean that if the value was realized
in 1994, and the return period is 100 years, then the next
3.2.50.1 Discussion—Damage from soil liquefaction results
occurrence will be in 2094. For example, earthquake occur- primarily from horizontal and vertical displacements of the
rences usually are considered as Poisson-distributed random
ground. This movement of the land surface can damage
variables, that is, variables where the probability is near buildings and buried utility lines such as gas mains, water lines
constantfromyeartoyear,andtheprobabilityofanoccurrence
and sewers, particularly at their connection to the building.
this year is independent of what happened last year. For a Extreme tilting or settlement of the building can occur if soil
Poisson random variable, the probability that the value will be
liquefaction occurs underneath the building foundations.
equaled or exceeded in its return period term is 63 %.
3.2.51 statistically consistent manner, n—following the
3.2.43 scenario expected loss (SEL), n—expected value of
mathematical rules and concepts of probability and statistics.
the scenario loss for the specified ground motion of the
3.2.52 structural component, n—component that is a part of
earthquake scenario selected.
a building’s lateral and/or vertical load-resisting system.
3.2.44 scenario loss (SL), n—earthquake damage loss ex-
3.2.53 third party reviewer, n—independent technically
pectationtobuildingsystemsandsiteimprovementsandwhere
qualified individual or organization that has not been engaged
User-prescribed, contents and/or related business interruption
in the design or modifications of the building(s) and is not in
loss, associated with specified earthquake events on specific
any way affiliated with the Provider.
fault(s) affecting the building.
3.2.53.1 Discussion—Third Party Review is conducted after
3.2.44.1 Discussion—SL values are expressed in terms of
the completion of the seismic risk assessment, rather than
the damage ratio. Dollar values can be determined by multi-
during the seismic risk assessment, by an Independent Re-
plying the damage ratio by the replacement cost estimate for
viewer. See 6.4 and 6.5.
the building. The SL is generally limited to earthquake loss
3.2.54 tsunami, n—long water waves that are generated
associated with the earthquake ground-shaking hazard, but
impulsively by tectonic displacements of the sea floor associ-
may include losses from other earthquake hazards, as pre-
ated with earthquakes.
scribed by a User.
3.2.54.1 Discussion—Tsunamis also may be caused by
3.2.45 scenario upper loss (SUL), n—scenario loss that has
eruption of a submarine volcano, submerged landslides, rock
a 10% percent probability of exceedance due to the specified
falls into the ocean, and underwater nuclear explosions.
ground motion of the scenario considered.
NOTE 1—Tectonic displacements with a substantial vertical (dip-slip)
3.2.46 seiche, n—water wave caused in an enclosed, or
component are more likely to cause tsunamis than are strike-slip displace-
partially enclosed, body of water in response to the passage of
ments. Wave heights associated with tsunamis in deep water generally are
seismic waves.
small; however, as the wave fronts approach coastlines where there is
shallow water, the wave heights increase and will run up onto the land.
3.2.47 senior assessor, n—the licensed engineer in respon-
Tsunami run-up can cause loss of life and substantial property damage.
sible charge of the management of the assessment who affirms
3.2.55 uncertainty, n—degree of random behavior repre-
and attests to the report’s content, findings, and conformance
sented by an applicable probability distribution and associated
with referenced ASTM requirements. See 6.2.3 for qualifica-
parameters.
tions required to perform such functions for Level 1 or higher
assessments.
3.2.56 uncertainty tolerance level, n—amount of uncer-
tainty in financial exposure that a User is willing to accept
3.2.48 significant damage, n—damage caused that is suffi-
resulting from the cost to remedy earthquake damage not
cienttorequireguidancefromalicensedengineertodetermine
identified by an seismic risk assessment.
extent of damage and necessary repairs to bring the building to
a pre-earthquake condition. 3.2.56.1 Discussion—Thiscanbeinfluencedbysuchfactors
as initial acquisition cost or equity contribution, mortgage
3.2.49 site visit, n—visual reconnaissance of the site and
underwriting considerations, specific terms of the equity
physical property by the FieldAssessor and those assisting the
position, projected term of the hold, etc.
Field Assessor to gather information on the physical property
for the purposes of preparing seismic risk assessment.
3.2.57 user, n—the party that retains the Provider to prepare
3.2.49.1 Discussion—The Provider is not expected to use or a seismic risk assessment of the property in accordance with
provide scaffolding, ladders, magnifying lenses, etc. in under- this Guide. A User may include a purchaser, potential client,
taking the visual reconnaissance of the building systems and owner, existing of potential mortgagee, lender or property
components during the site visit. The User is expected to manager of the subject property.
E2026 − 16a
4. Significance and Use confirmation, that the building is in the condition it was at the
time of assessment and that the understanding of seismic
4.1 Uses—This Guide is intended for use on a voluntary
hazards and performance of the specific building type have not
basis by parties such as lenders, loan servicers, insurers and
changed.
equity investors in real estate (Users) who wish to estimate
4.1.4 Availability of Information—This guide recognizes
possible earthquake losses to buildings. This guide outlines
that a Provider’s opinions and observations may be affected or
procedures for conducting a seismic risk assessment for a
contingent on information (or the lack thereof) that is readily
specific User considering the User’s requirements for due
available to the Provider during the conduct of an investiga-
diligence.ThespecificpurposeofthisguideistoprovideUsers
tion.Forinstance,aProvider’sobservationsmaybeaffectedby
with seismic risk assessment during the anticipated term for
the number of people using the building or the availability of
holding either the mortgage or the deed. A seismic risk
property management to provide information, such as the
assessment prepared in accordance with this guide should
construction documents.
reference or state that the guidance in this document was used
4.1.5 Site-Specific—Seismic risk assessments are site-
as a basis for the report and should also identify any deviations
specific in that they relate to estimation of earthquake loss to
from the guidelines. This guide is intended to reflect a
building(s) located at a specific site.
commercially prudent and reasonable investigation for perfor-
4.2 Principles—Thefollowingprinciplesareanintegralpart
mance of seismic risk assessments.
of this guide and should be referred to in resolving any
4.1.1 Users—This Guide is designed to assist the User in
ambiguity or exercising such discretion as is accorded the User
developing information about the earthquake-related damage
or the Provider in estimating loss to buildings from earth-
potential of a building, or groups of buildings.
quakes. The principles should also be used in judging whether
4.1.1.1 Use of this guide may permit a User to satisfy, in
a User or Provider has conducted an appropriate assessment
part, their requirements for due diligence in assessing a
and estimation of earthquake loss to a building.
building’s potential for losses associated with earthquakes for
4.2.1 Uncertainty Not Eliminated—No estimate can wholly
real estate transactions.
eliminate uncertainty regarding damage resulting from actual
4.1.2 Types of Investigations—This guide provides sug-
earthquakes. The successive levels of investigation described
gestedapproachesfortheperformanceoffivedifferenttypesof
in this Guide are intended to reduce, but not eliminate,
assessments. Each is intended to serve different financial and
uncertainty regarding the estimation of damage. This Guide
management needs of the User. Several of these types of
acknowledges the reasonable limits of time and cost related to
assessment specifically depend on characterization of the
a selected level of assessment.
earthquake ground motion as given in Section 7.
4.2.2 Not Exhaustive—There is a point at which the cost to
4.1.2.1 Building Stability (BS)—Assessment of whether the
gather information outweighs the usefulness of the information
building will maintain vertical load-carrying capacity in whole
and, in fact, may be detrimental to the orderly completion of
or in part during considered earthquake ground motions (see
transactions within the resources available to support the
Section 8).
investigation. This Guide identifies and suggests that a balance
4.1.2.2 Site Stability (SS)—Assessment of the likelihood
be sought between the competing goals of limiting the costs
thatthesitewillremainstableinearthquakesandisnotsubject
and time demands versus limiting the resulting uncertainty
to failure through faulting, soil liquefaction, landslide, or other
regarding unknown conditions or information by acquiring as
site response that may threaten the building’s stability or cause
much information as possible.
significant damage (see Section 9).
4.1.2.3 Building Damageability (BD)—Assessment of the
NOTE 2—Appropriate due diligence according to this Guide is not to be
construed as technically exhaustive. There is a point at which the cost of
damageability of the building(s) during earthquake ground
information obtained or the time required to conduct the seismic risk
motions and the degree of damage expected over time. The
assessment may outweigh the usefulness of the information and, in fact,
assessment includes performing and completing the building
may be a material detriment to the orderly and timely completion of a
damageability assessment as either a probable loss (PL) or a
commercial real estate transaction. It is the intent of this Guide to attempt
scenario loss (SL) assessment, or both (see Section 10). toidentifyabalancebetweenlimitingthecostsandtimedemandsinherent
in performing a seismic risk assessment and reducing the uncertainty
4.1.2.4 Contents Damageability (CD)—Assessment of the
about unknown physical deficiencies resulting from completing additional
damageability of the contents to earthquake ground motions.
inquiry.
Thisguidesuggeststhatthecontentsdamageabilityassessment
4.2.3 Level of Investigation—Not every property warrants
be performed using the SL assessment approach (see Section
the same level of investigation. Consistent with good commer-
11).
cial or customary practice, choosing the appropriate level of
4.1.2.5 Business Interruption (BI)—Assessment of the im-
investigation is guided by the type and age of buildings subject
plicationsforcontinueduseorpartialuseofthebuildingforits
to assessment, the resources and time available, the anticipated
intended purpose due to earthquake damage, whether to the
severityofshaking,theexpertiseandrisktoleranceoftheUser,
building systems, or contents, or both.This guide suggests that
and the information developed during the course of the
thebusinessinterruptionassessmentbeperformedusingtheSL
investigation.
assessment approach (see Section 12).
4.1.3 Application and Temporal Relevance of Report—The 4.3 Subsequent Use of Seismic Risk Assessments—This
User should only rely on a seismic risk assessment report for guide recognizes that assessments of buildings prepared for
the specific purpose that it was intended, and upon specified levels of investigation and performed on the basis of
E2026 − 16a
the approaches discussed herein may include information that 5. Assessment Methodology and Approach
subsequent Users will want to use to avoid undertaking
5.1 Minimum Requirements:
duplicative investigations. Consequently, this guide describes
5.1.1 Seismic risk assessments may be performed for an
procedures to assist subsequent Users in determining how
individual building or a group of buildings.
appropriate it would be to use these results. Usage of prior
5.1.2 At the minimum, a seismic risk assessment should
reports is based on the following principles that should be
include an assessment of building stability (BS, Section 8) and
adheredtoinadditiontothespecificproceduressetforthinthis
site stability (SS, Section 9). It may also include a building
guide.
damageability (BD, Section 10), contents damageability (C,
4.3.1 Comparability—An estimate of loss to buildings from
Section 11), and/or business interruption (B, Section 12)
earthquakes is not to deemed as inappropriate merely because assessment, or any combination of these.
it did not identify all potentially vulnerable areas in connection
5.1.3 An earthquake ground motion assessment (Section 7)
with a building or a group of buildings. Seismic risk assess-
should be conducted in conjunction with all seismic risk
ments must be evaluated based on the reasonableness of assessments.
judgments made at the time and under the circumstances in 5.1.4 The User shall select any level of investigation for
which they were made. The result of any subsequent seismic these assessments (Levels 0 through 3).
riskassessmentsperformedtosimilarparametersshouldnotbe
5.1.5 The building damageability portion of the assessment
considered as valid standards to judge the appropriateness of (Section 10) may report a SL, where the specific scenario and
any prior seismic risk assessment based on hindsight, new the statistical measure reported or the probability of excee-
dance are given, or a PL with specified probability of excee-
information, use of developing technology or analytical
techniques, or other factors. dance and time period, or both.
5.1.6 The contents damageability (Section 11) and business
4.3.2 Use of Prior Information—Users and Providers may
interruption (Section 12) portions of the assessment should be
use information in prior reports that meet or exceed the
reported on the basis of a scenario loss approach.
requirements of this guide for specified levels of investigation
5.1.7 Retrofit—Insomecases,informationonretrofittingthe
and then only provided that the specific procedures set forth in
building may be requested by the User under specified
the guide were met, including the qualification of the Provider.
conditions, typically instability or damage exceeding a thresh-
4.3.3 Prior Assessment Meets or Exceeds—A prior seismic
old value. In such cases, recommendations should be devel-
risk assessment report prepared for specified levels of investi-
oped for modifications of the building’s structural or non-
gation may be used in its entirety, without regard to specific
structural systems, or both, including members and
procedures set forth in this guide, if in the judgment of the
connections, aimed at the assessed conditions. The required
Provider, the prior report was prepared for specified levels of
assessment should be performed for both the building in its
investigation meeting or exceeding the requirements of this
existing condition and for the retrofitted building condition(s),
Guide and the conditions of the building(s) and the seismic
assuming the retrofit is completed as recommended with good
hazards affecting the site are not likely to have changed
professional practice.
materially since the prior report was prepared. In making this
5.1.8 The use of any interactive computer assessment tools
judgment, the Provider should consider the types of building
developed specifically to assess the earthquake loss and requir-
construction assessed in the report, any new information
ing only general information about the building and site (for
related to the behavior of that specific building construction
example, structure type) should be limited to Level 0 (screen-
type in recent earthquakes, as well as current understanding of
ing level) assessments.
the site conditions.
5.2 Level of Investigation:
4.3.4 Current Investigation—Prior seismic risk assessments
5.2.1 Seismic risk assessments may consider varying de-
should not be used without current investigation of conditions
grees of assessment of a building or buildings from Level 0 to
likely to affect the current seismic risk assessment. Likely
Level 3.
conditions include the current level of knowledge on and
5.2.2 Four levels of investigation are described (Level 0
experience with building constructions of particular types in
through Level 3), except for the assessment of ground motion
recentearthquakes,aswellas,currentunderstandingofthesite
for which there are three levels (Level 0 through Level 2).
conditions that differ from those in existence when the prior
5.2.3 Level 0 is a screening investigation, while Level 3 is
report was prepared.
a highly detailed technical investigation. Levels 1 and 2 are
4.3.5 Actual Knowledge Exception—If the User or Provider
intermediate between these two.
has actual knowledge that the information being used from a
5.2.4 The selection of the level of the investigations per-
prior seismic risk assessment report is not accurate or is
formed should be guided by the expected level of uncertainty
suspected of being inaccurate, then such information from a
in the result that is acceptable to the User. The lower the
prior report should not be used.
tolerance for uncertainty, the higher the Level of investigation
shouldbe.Thehighertheseismichazardoftheregioninwhich
4.4 When a new seismic risk assessment is performed for
the building(s) is located, the higher the level of assessment
thesameUserthatisconsistentwiththisguideandhasahigher
should be, all other things being equal.
level of investigation than a prior investigation, then the new
investigation should supersede the former one. 5.3 Seismic Risk Assessment for Multiple Buildings:
E2026 − 16a
5.3.1 Where projects consist of multiple buildings or build- 6.1.3 There are three main qualifications that bear on the
ing structural units (sections) where earthquake impacts are ability of the Provider to reliably give professional opinions on
independent of each other, one or more of the following should the earthquake hazard posed by a site and the losses to a
be presented in the building loss assessment: building:
5.3.1.1 Building loss results for each individual building or 6.1.3.1 Knowledge of the current state of understanding and
application of the underlying professional and scientific disci-
building sections, in addition to those of the group. These
results may be expressed as an expected, mean, range, or plines that bear on the particular practice; and
6.1.3.2 Experience in application of the specific profes-
statistic, for example, a value with 10 % probability of excee-
dance; sional skills required for seismic evaluation of the specific
buildings and conditions of the subject site or building.
5.3.1.2 Mean and standard deviation of loss for each build-
6.1.3.3 All Providers of Level 1 and higher inquiries should
ing or building section for selected specific events, or for the
have a working knowledge of ASCE 41 and ASCE 7.
ground motion probability distribution at the site(s);
6.1.4 User’s Responsibilities:
5.3.1.3 SL or PL values for a group of buildings must be
6.1.4.1 User Requirements—Specific technical require-
determined using a statistically valid approach, including
ments for the study including the level of each assessment, if
weighting of the contribution statistics by the relative replace-
any, including ground motion, site stability, building stability,
ment values for each element of the group.
building damageability, building content, and/or interruption,
5.3.1.4 Aggregate PL’s and SL’s for a group of buildings
that shall be prepared.
must be determined in a manner that is consistent with the
6.1.4.2 Access to Property and Records—The User should
assumptions of the damage statistics model used. If the
arrange for or provide the Provider with timely access to all
individual buildings are co-located and are subject to earth-
reports, drawings, and specifications for the building(s), both
quake ground motions of the same intensity (consistent with
for the original building and for any modifications, alterations
the statistical distribution of the damage model), then conven-
or additions. This should include all geotechnical reports and
tional statistical sampling methods can be applied to determine
analysesofthesiteandanyreportsofengineeringinvestigation
aggregate damage statistics. If they are not, which will be
of the building, particularly those following earthquakes.
typicalforgeographicallydispersedgroups,thenmoredetailed
Where not on hand, these records of
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2026 − 16 E2026 − 16a An American National Standard
Standard Guide for
Seismic Risk Assessment of Buildings
This standard is issued under the fixed designation E2026; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Lenders, insurers, and equity owners in real estate are giving more intense scrutiny to earthquake
risk than ever before. The 1989 Loma Prieta, California earthquake, which caused more than $6 billion
in damage, accelerated the trend toward considering loss estimation in real estate transactions. The
1994 Northridge, California earthquake, with over $20 billion in damage, made seismic risk
assessment an integral part of real estate financial decision-making for regions at risk of damaging
earthquakes. Users of Seismic Risk Assessment reports need specific and consistent measures for
assessing the possibility of future loss due to earthquake occurrences. This guide discusses specific
approaches that the real estate and technical communities can consider a basis for characterizing the
seismic risk assessment of buildings in an earthquake. It uses two concepts to characterize earthquake
loss: probable loss (PL) and scenario loss (SL). Use of the term probable maximum loss (PML) is
acceptable, provided it is specifically and adequately defined by the User.
1. Scope
1.1 This guide provides guidance on conducting seismic risk assessments for buildings. As such, this guide assists a User to
assess a property’s potential for losses from earthquake occurrences.
1.1.1 Hazards addressed in this guide include:
1.1.1.1 Earthquake ground shaking,
1.1.1.2 Earthquake-caused site instability, including fault rupture, landslides, soil liquefaction, lateral spreading and settlement,
and
1.1.1.3 Earthquake-caused off-site response impacting the property, including flooding from dam or dike failure, tsunamis and
seiches.
1.1.2 This guide does not address the following:
1.1.2.1 Earthquake-caused fires and toxic materials releases.
1.1.2.2 Federal, state, or local laws and regulations of building construction or maintenance. Users are cautioned that current
federal, state, and local laws and regulations may differ from those in effect at the time of the original construction of the
building(s).
1.1.2.3 Preservation of life safety.
1.1.2.4 Prevention of building damage.
1.1.2.5 Contractual and legal obligations between prior and subsequent Users of seismic risk assessment reports or between
Providers who prepared the report and those who would like to use such prior reports.
1.1.2.6 Contractual and legal obligations between a Provider and a User, and other parties, if any.
1.1.3 It is the responsibility of the User of this guide to establish appropriate life safety and damage prevention practices and
determine the applicability of current regulatory limitations prior to use.
1.2 The objectives of this guide are:
1.2.1 To synthesize and document guidelines for seismic risk assessment of buildings;
1.2.2 To encourage standardized seismic risk assessments;
1.2.3 To establish guidelines for field observations of the site and physical conditions, and the document review and research
considered appropriate, practical, sufficient, and reasonable for seismic risk assessment;
This guide is under the jurisdiction of ASTM Committee E06 on Performance of Buildings and is the direct responsibility of Subcommittee E06.25 on Whole Buildings
and Facilities.
Current edition approved Jan. 1, 2016May 15, 2016. Published June 2016. Originally approved in 1999. Last previous edition approved in 20072016 as E2026-07.-16.
DOI: 10.1520/E2026-16.10.1520/E2026-16A.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2026 − 16a
1.2.4 To establish guidelines on what reasonably can be expected of and delivered by a Provider in conducting the seismic risk
assessment of buildings; and
1.2.5 To establish guidelines by which a Provider can communicate to the User observations, opinions, and conclusions in a
manner that is meaningful and not misleading either by content or by omission.
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
2. Referenced Documents
2.1 ASTM Standards:
E631 Terminology of Building Constructions
2.2 ICC Standard:
IBC International Building Code, current edition
2.3 Other References—The following resource documents provide technical guidance for the seismic evaluation and retrofit of
existing buildings:
ASCE 7-10 Minimum Design Loads for Buildings and Other Structures
ASCE 31 Seismic Evaluation of Existing Buildings
ASCE 41-13 Seismic Evaluation and Retrofit of Existing Buildings
3. Terminology
3.1 Definitions:
3.1.1 See Terminology E631.
3.1.2 For definition of terms related to building construction, ASCE 31 and ASCE 41 provide additional resources for
understanding terminology and language related to seismic performance of buildings.
3.1.3 For definition of terms and additional detailed information on concepts related to seismic events and structural design, see
references at the end of this document.
3.2 Definitions of Terms Specific to This Standard—This section provides definitions of concepts and terms specific to this guide.
The concepts and terms are an integral part of this guide and are critical to an understanding of this guide and its use.
3.2.1 active earthquake fault, n—an earthquake fault that has exhibited surface displacement within Holocene time typically
about the last 11 000 years.
3.2.2 building code, n—a collection of laws (regulations, ordinances, or statutory requirements) applicable to buildings, adopted
by governmental (legislative) authority and administered with the primary intent of protecting public health, safety, and welfare.
3.2.3 building systems, n—all physical systems that comprise a building and its services.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from International Code Council (ICC), 500 New Jersey Ave., NW, 6th Floor, Washington, DC 20001, http://www.iccsafe.org.
Available from American Society of Civil Engineers (ASCE), 1801 Alexander Bell Dr., Reston, VA 20191, http://www.asce.org.
The successor of FEMA 310 issued as a standard in 2003, with periodic revisions.
The successor of FEMA 356 issued as a standard in 2006, with periodic revisions.
3.2.3.1 Discussion—
This includes architectural, structural, mechanical, plumbing, electrical, fire life-safety, vertical transportation and security systems.
More specifically architectural systems include non-structural building envelopes, roofing, ceilings, partitions, non-structural
demising walls etc; structural systems include both gravity and seismic force-resisting systems and foundations; mechanical
systems include heating, ventilating and air conditioning equipment, ducts, control systems etc; plumbing systems include
domestic water heaters, piping, controls, plumbing fixtures, waste water system piping and natural gas or propane systems, storm
water drains and pumps etc; electrical systems include switchgear, transformers, breakers, wiring, lighting fixtures, emergency
power systems etc; and fire life-safety systems include fire sprinkler systems, monitoring and alarm systems etc. Not included in
building systems are those contained within a building and defined as contents.
3.2.4 business interruption, n—a period of interruption to normal business operations that can potentially or materially cause
a loss to the owner/operator of that business through loss of use of the building until use is restored consistent with business
operations.
3.2.4.1 Discussion—
E2026 − 16a
The loss may be partial or total for the period under consideration. Business interruption is expressed in days/weeks/months of
downtime for the building as a whole or the equivalent operating value.
3.2.5 construction documents, n—documents used in the initial construction phase and any subsequent modification(s) of
building(s) for which the seismic risk assessment is prepared. Construction documents include drawings, calculations,
specifications, geotechnical reports, construction reports, and testing results.
3.2.5.1 Discussion—
Generally as-built plans are the preferred form of construction documents.
3.2.6 contents, n—elements contained within the building that are not defined as building systems.
3.2.6.1 Discussion—
Examples include tenant-installed equipment, storage racks, material handling systems, shelving, stored inventories, furniture,
fixtures, office machines, computer equipment, filing cabinets, and personal property.
3.2.7 correlation, n—the tendency or likelihood of the behavior of one element to be influenced by the known behavior of
another element.
3.2.8 damage or repair cost, n—cost required to restore the building to its pre-earthquake condition, allowing for salvage and
demolition.
3.2.8.1 Discussion—
The value includes hard costs of construction as well as soft costs for design, site supervision, management, etc. (See also
replacement cost.)
3.2.9 damage ratio, n—ratio of the damage or repair cost divided by the replacement cost.
3.2.10 dangerous conditions, n—situations that pose a threat or possible injury to the occupants or adjacent area consistent with
IBC definition.
3.2.11 deficiency, n—conspicuous defect(s) in the building or significant deferred maintenance items of a building and its
components or equipment.
3.2.11.1 Discussion—
Conditions resulting from the lack of routine maintenance, miscellaneous repairs, operating maintenance, etc. are not considered
a deficiency.
3.2.12 demand surge, n—a temporary economic condition following a large or great earthquake in which the increased demand
for materials, labor, and services results in an increase in the cost and time to repair damage to buildings compared to the cost and
time to repair the same damage under normal conditions or following smaller earthquakes.
3.2.12.1 Discussion—
The phenomenon results from a complex time-dependent process of supply and demand. Objective and complete datasets for
demand surge for large to great earthquakes in the United States are unavailable, as are peer-reviewed public models to reliably
predict the effects of demand surge.
3.2.13 design basis earthquake (DBE), n—the site ground motion with a 10 % probability of exceedance in 50 years, equivalent
to a 475-year return period for exceedance, or a 0.2105 % annual probability of occurrence.
3.2.13.1 Discussion—
The design basis earthquake ground motions are associated with any earthquake that has the specified site ground motion value;
often there are several earthquakes with different magnitudes and causative faults that yield equivalent site peak ground motions.
3.2.14 distribution function, n—the probability distribution for a random variable.
3.2.14.1 Discussion—
E2026 − 16a
7,8,9
The random variable may include such things as loss, ground motion, or other consequence of earthquake occurrence.
3.2.15 due diligence, n—the assessment of the condition of a property for the purposes of identifying conditions or
characteristics of the property, including potentially dangerous conditions, that may be important to determining the appropriate-
ness of the property for financial or real estate transactions.
Earthquake Damage Evaluation Data for California, Report ATC-13, Applied Technology Council, Redwood City, CA, 1985. ATC-13-1 issued in 2003.
Thiel, C. C., and Zsutty, T. C., “Earthquake Characteristics and Damage Statistics,” Earthquake Spectra, Earthquake Engineering Research Institute, Oakland, CA, Vol
3, No. 4, November 1987.
Richter, C. F., Elementary Seismology, W.H. Freeman, San Francisco, CA, 1958.
3.2.15.1 Discussion—
The extent of due diligence exercised on behalf of a User is usually related to the User’s tolerance for uncertainty, the purpose of
seismic risk assessment, the resources and time available to the Provider to conduct the site visit and review construction
documents.
3.2.16 expected value, n—of a random variable, the average or mean of the distribution function.
3.2.16.1 Discussion—
The expected value is determined as the sum (or integral) of all the values that can occur multiplied by the probability of their
occurrence. (Compare: median value.)
3.2.17 fault zone, n—area within a prescribed distance from any of the surface traces of a fault.
3.2.17.1 Discussion—
The distance depends on the magnitude of earthquakes that could occur on the fault—typically 500 ft (152 m) from major faults,
which are those capable of earthquakes with magnitudes of 6.5 or greater, and 250 ft (761 m) away from other well-defined faults.
Within California, the fault zones are determined by the California Geological Survey under the Earthquake Special Studies Zones
Act for active and potentially active faults that have been identified by the state or other governmental bodies.
3.2.18 field assessor, n—the person assigned by the Senior Assessor who conducts the site visits of the property to observe,
evaluate, and document the lateral load-resisting system. Other qualified persons may assist the Field Assessor. See 6.2.3 for
qualifications required to perform such functions for Level 1 or higher assessments.
3.2.19 independent reviewer, n—independent technically qualified individual or organization that has not been engaged in the
design or modifications of the building(s), and is not in any way affiliated with the Provider.
3.2.19.1 Discussion—
The concept may also be represented by the phrase “Independent Peer Reviewer.” Independent Review is conducted during the
seismic risk assessment (and typically involves interaction with the Provider) rather than after the completion of the seismic risk
assessment by a Third Party Reviewer. See 6.4 and 6.5.
3.2.20 interdependency, n—a condition wherein the function of the building is dependent on another building, on utilities, or
on other critical elements in the supply chain.
3.2.20.1 Discussion—
Other critical elements include transportation and may include a customer, vendor (for example, supplier of materials), contractor
(supplier of services), staff (for example, supplier of staff), information (for example, data processing for accounting or
distribution), etc.
3.2.21 landslide, n—(1) ground motion, the rapid downslope movement of soil or rock material, or both, often lubricated by
ground water, over a basal shear zone; and (2) geological, stationary material deposited in the past by the rapid downslope
movement of soil or rock material, or both.
3.2.22 lateral load-resisting system, n—the elements of the buildingstructural system that resist the vertical, horizontal, and
torsional provide support and stability to the building under seismic and wind forces applied to the building.forces.
3.2.23 magnitude of earthquake, n—any of a variety of measures that indicates the “size” or “energy release” of an earthquake.
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3.2.23.1 Discussion—
At least 20 different magnitude scales are in use within the technical community. The most commonly used lay term is the Richter
magnitude, which is determined by taking the common logarithm (base 10) of the largest ground motion recorded during the arrival
of a “P” wave, or seismic surface wave, and applying a standard correction for the distance to the epicenter of the earthquake. The
measure most widely used in the technical community is the moment magnitude, a measure of the total strain energy released in
the event. Magnitudes calculated using different scales can vary widely for the same earthquake.
3.2.24 maximum capable earthquake (MCE), n—earthquake that can occur within the region that produces the largest average
ground motion at the site of interest.
3.2.24.1 Discussion—
This is NOT the same as the ASCE 7 definition of risk-targeted maximum considered earthquake (MCE ), or past definitions of
R
maximum considered earthquake (MCE) as found in ASCE 7 or ASCE 41. The concept of maximum capable earthquake (MCE)
for purposes of the Guide is a deterministic event, and does not include a return period value.
3.2.25 median value, n—value that divides the distribution function into equal parts, such that the value of the random variable
has an equal probability of being above or below the reference value. (Compare expected value.)
3.2.26 Modified Mercalli Intensity (MMI), n—qualitative description of the local effects of the earthquake at a site.
3.2.26.1 Discussion—
Normally, MMI is given as a roman numeral, from I to XII, to emphasize its qualitative, not quantitative, nature. A single
earthquake can have many different MMI intensities assigned over the region in which the earthquake is felt. Use of MMI to
characterize ground motions for use in the seismic risk assessment of buildings should be done with caution because the damage
level predicted is associated with a very wide range of earthquake ground motions, not a specific earthquake ground motion.
3.2.27 non-structural components, n—components of a building system that are not part of the vertical or lateral-load resisting
structural systems nor are defined as contents.
3.2.28 observations, n—the relevant information or measurements, or combination thereof, documented during the site visit
survey.
3.2.29 obvious, adj—readily accessible and can be seen easily by the Provider without the aid of any instrument or device during
a site visit.
3.2.30 occupant, n—of a building, an individual or individuals, who is or will be occupying space in a particular building(s)
under study, or a part thereof.
3.2.30.1 Discussion—
Persons who are authorized to be present only temporarily, or in special circumstances such as those permitted to pass through
during an emergency, are visitors.
3.2.31 other earthquake hazards, n—other earthquake hazards include, but are not limited to, soil liquefaction; ground
deformation including subsidence, rupture, differential settlement, landsliding, slumping, etc; and, hazards from off-site response
to the earthquake including flooding from dam or dike failure, tsunami, or seiche.
3.2.32 owner, n—the entity or individual holding the deed to the building, or their designated representative. An agent or
contractor may be considered an owner in some circumstances.
3.2.33 P-delta effect, n—the secondary effect of column axial loads and lateral deflections on the shears and moments in various
components of a building.
3.2.34 peak ground acceleration, (PGA), n—the maximum acceleration at a site caused by an earthquake ground motion. PGA
may be an actual recording or an estimate. PGA is most often given as the maximum of the horizontal components and is usually
2 2
expressed as a fraction of gravitational acceleration, g, 32.2 ft/s (9.8 m/s ). The terms effective peak acceleration (EPA) and/or
effective maximum acceleration (EMA) are sometimes used in seismic analysis. Where EPA and EMA are used, the basis for
determination and justification of use should be provided, including verification that the use requires this representation of ground
motion as distinct from others.
3.2.35 potentially active fault, n—a fault that shows evidence of surface displacement during the Quaternary period
(approximately the last two million years).
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3.2.35.1 Discussion—
This is the definition used in Earthquake Fault Zones (previously referred to as Alquist-Priolo Special Study Zones) in California.
Other definitions may be appropriate in different seismic hazard regions. The point of the definition is to preclude concern for faults
that have not moved in a very long time; that is, much longer time periods, such as those that dominate the Eastern and Midwestern
portions of the United States.
3.2.36 probabilistic ground motion, n—earthquake ground motions for the building site that are determined from an evaluation
of the seismic exposure for the site for a given time period and are represented by a probability distribution function. Where
appropriate, the ground motion assessment process should reflect conditional probabilities of the temporal dependence of
earthquakes on specific seismic features, where they are known.
3.2.37 probable loss (PL), n—earthquake loss to the building systems that has a specified probability of being exceeded in a
given time period, or an earthquake loss that has a specified return period for exceedance.
3.2.37.1 Discussion—
This value is meant to reflect in a statistically consistent computational manner all of the uncertainties that can impact damage,
including when and where earthquakes occur and with what magnitude, attenuations of ground motion to the site, local site effects
and performance of the building systems in this ground motion. The PL is expressed in terms of the damage ratio and is generally
limited to earthquake loss associated with the earthquake ground-shaking hazard, but may include losses from other earthquake
hazards as prescribed by a User. Dollar values can be determined by multiplying the damage ratio by the replacement cost estimate
for the building. Where seismic analysis of discounted present value is to be performed then annual PL, mean and standard
deviation are appropriate damageability measures for use in such application.
3.2.38 probable maximum loss (PML), n—term historically used to characterize building damageability in earthquakes.
3.2.38.1 Discussion—
PML has had a number of very different explicit and implicit definitions. The concepts of probable loss (PL) and scenario loss (SL)
are used in this guide to characterize the earthquake losses of an individual building or groups of buildings. When a Provider uses
the term PML, it should be defined in terms of SL or PL as defined herein.
3.2.39 provider, n—person or organization that prepares a report and is responsible for the findings of the seismic risk
assessment of a building or group of buildings.
3.2.40 replacement cost, n—cost required to construct an entirely new building of the same size, envelope, configuration and
character as the referenced building, assuming a virgin site.
3.2.40.1 Discussion—
Replacement cost includes costs for construction, including building materials and labor; design; site supervision; management;
etc.
3.2.41 retrofit scheme, n—preliminary suggestion(s) of modifications or additions to the building intended to correct, mitigate,
or repair a physical deficiency that will improve the seismic performance of the building so that it is acceptable to the User.
3.2.42 return period, n—of a random variable, is the inverse of the annual probability that the value is equaled or exceeded.
3.2.42.1 Discussion—
Return period is not the time period between occurrences of the value, but is the long-term average of the random times between
occurrences. Often, return period is incorrectly interpreted to mean that if the value was realized in 1994, and the return period
is 100 years, then the next occurrence will be in 2094. For example, earthquake occurrences usually are considered as
Poisson-distributed random variables, that is, variables where the probability is near constant from year to year, and the probability
of an occurrence this year is independent of what happened last year. For a Poisson random variable, the probability that the value
will be equaled or exceeded in its return period term is 63 %.
3.2.43 scenario expected loss (SEL), n—expected value of the scenario loss for the specified ground motion of the earthquake
scenario selected.
3.2.44 scenario loss (SL), n—earthquake damage loss expectation to building systems and site improvements and where
User-prescribed, contents and/or related business interruption loss, associated with specified earthquake events on specific fault(s)
affecting the building.
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3.2.44.1 Discussion—
SL values are expressed in terms of the damage ratio. Dollar values can be determined by multiplying the damage ratio by the
replacement cost estimate for the building. The SL is generally limited to earthquake loss associated with the earthquake
ground-shaking hazard, but may include losses from other earthquake hazards, as prescribed by a User.
3.2.45 scenario upper loss (SUL), n—scenario loss that has a 10% percent probability of exceedance due to the specified ground
motion of the scenario considered.
3.2.46 seiche, n—water wave caused in an enclosed, or partially enclosed, body of water in response to the passage of seismic
waves.
3.2.47 senior assessor, n—the licensed engineer in responsible charge of the management of the assessment who affirms and
attests to the report’s content, findings, and conformance with referenced ASTM requirements. See 6.2.3 for qualifications required
to perform such functions for Level 1 or higher assessments.
3.2.48 significant damage, n—damage caused that is sufficient to require guidance from a licensed engineer to determine extent
of damage and necessary repairs to bring the building to a pre-earthquake condition.
3.2.49 site visit, n—visual reconnaissance of the site and physical property by the Field Assessor and those assisting the Field
Assessor to gather information on the physical property for the purposes of preparing seismic risk assessment.
3.2.49.1 Discussion—
The Provider is not expected to use or provide scaffolding, ladders, magnifying lenses, etc. in undertaking the visual
reconnaissance of the building systems and components during the site visit. The User is expected to provide on-site ladders, if
available, and to provide safe access to all parts of the structure, including the roof. This definition implies that such a visit is
preliminary, not in-depth, and typically done without the aid of exploratory probing, removal of materials, or testing. It is literally
the Provider’s (Field Assessor’s) visual survey of the building(s) and site improvements.
3.2.50 soil liquefaction, n—the transformation of loose, saturated, sandy soil materials into a fluid-like state.
3.2.50.1 Discussion—
Damage from soil liquefaction results primarily from horizontal and vertical displacements of the ground. This movement of the
land surface can damage buildings and buried utility lines such as gas mains, water lines and sewers, particularly at their
connection to the building. Extreme tilting or settlement of the building can occur if soil liquefaction occurs underneath the
building foundations.
3.2.51 statistically consistent manner, n—following the mathematical rules and concepts of probability and statistics.
3.2.52 structural component, n—component that is a part of a building’s lateral and/or vertical load-resisting system.
3.2.53 third party reviewer, n—independent technically qualified individual or organization that has not been engaged in the
design or modifications of the building(s) and is not in any way affiliated with the Provider.
3.2.53.1 Discussion—
Third Party Review is conducted after the completion of the seismic risk assessment, rather than during the seismic risk
assessment, by an Independent Reviewer. See 6.4 and 6.5.
3.2.54 tsunami, n—long water waves that are generated impulsively by tectonic displacements of the sea floor associated with
earthquakes.
3.2.54.1 Discussion—
Tsunamis also may be caused by eruption of a submarine volcano, submerged landslides, rock falls into the ocean, and underwater
nuclear explosions.
NOTE 1—Tectonic displacements with a substantial vertical (dip-slip) component are more likely to cause tsunamis than are strike-slip displacements.
Wave heights associated with tsunamis in deep water generally are small; however, as the wave fronts approach coastlines where there is shallow water,
the wave heights increase and will run up onto the land. Tsunami run-up can cause loss of life and substantial property damage.
3.2.55 uncertainty, n—degree of random behavior represented by an applicable probability distribution and associated
parameters.
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3.2.56 uncertainty tolerance level, n—amount of uncertainty in financial exposure that a User is willing to accept resulting from
the cost to remedy earthquake damage not identified by an seismic risk assessment.
3.2.56.1 Discussion—
This can be influenced by such factors as initial acquisition cost or equity contribution, mortgage underwriting considerations,
specific terms of the equity position, projected term of the hold, etc.
3.2.57 user, n—the party that retains the Provider to prepare a seismic risk assessment of the property in accordance with this
Guide. A User may include a purchaser, potential client, owner, existing of potential mortgagee, lender or property manager of the
subject property.
4. Significance and Use
4.1 Uses—This Guide is intended for use on a voluntary basis by parties such as lenders, loan servicers, insurers and equity
investors in real estate (Users) who wish to estimate possible earthquake losses to buildings. This guide outlines procedures for
conducting a seismic risk assessment for a specific User considering the User’s requirements for due diligence. The specific
purpose of this guide is to provide Users with seismic risk assessment during the anticipated term for holding either the mortgage
or the deed. A seismic risk assessment prepared in accordance with this guide should reference or state that the guidance in this
document was used as a basis for the report and should also identify any deviations from the guidelines. This guide is intended
to reflect a commercially prudent and reasonable investigation for performance of seismic risk assessments.
4.1.1 Users—This Guide is designed to assist the User in developing information about the earthquake-related damage potential
of a building, or groups of buildings.
4.1.1.1 Use of this guide may permit a User to satisfy, in part, their requirements for due diligence in assessing a building’s
potential for losses associated with earthquakes for real estate transactions.
4.1.2 Types of Investigations—This guide provides suggested approaches for the performance of five different types of
assessments. Each is intended to serve different financial and management needs of the User. Several of these types of assessment
specifically depend on characterization of the earthquake ground motion as given in Section 7.
4.1.2.1 Building Stability (BS)—Assessment of whether the building will maintain vertical load-carrying capacity in whole or
in part during considered earthquake ground motions (see Section 8).
4.1.2.2 Site Stability (SS)—Assessment of the likelihood that the site will remain stable in earthquakes and is not subject to
failure through faulting, soil liquefaction, landslide, or other site response that may threaten the building’s stability or cause
significant damage (see Section 9).
4.1.2.3 Building Damageability (BD)—Assessment of the damageability of the building(s) during earthquake ground motions
and the degree of damage expected over time. The assessment includes performing and completing the building damageability
assessment as either a probable loss (PL) or a scenario loss (SL) assessment, or both (see Section 10).
4.1.2.4 Contents Damageability (CD)—Assessment of the damageability of the contents to earthquake ground motions. This
guide suggests that the contents damageability assessment be performed using the SL assessment approach (see Section 11).
4.1.2.5 Business Interruption (BI)—Assessment of the implications for continued use or partial use of the building for its
intended purpose due to earthquake damage, whether to the building systems, or contents, or both. This guide suggests that the
business interruption assessment be performed using the SL assessment approach (see Section 12).
4.1.3 Application and Temporal Relevance of Report—Any new User of a prior study The User should only rely on the study
for the a seismic risk assessment report for the specific purpose that it was commissioned. At the request of the new User the
Provider should confirm intended, and upon confirmation, that the building is in the condition it was at the time of assessment as
documented in the report and that the understanding of seismic hazards and performance of the specific building type have not
changed.
4.1.4 Availability of Information—This guide recognizes that a Provider’s opinions and observations may be affected or
contingent on information (or the lack thereof) that is readily available to the Provider during the conduct of an investigation. For
instance, a Provider’s observations may be affected by the number of people using the building or the availability of property
management to provide information, such as the construction documents.
4.1.5 Site-Specific—Seismic risk assessments are site-specific in that they relate to estimation of earthquake loss to building(s)
located at a specific site.
4.2 Principles—The following principles are an integral part of this guide and should be referred to in resolving any ambiguity
or exercising such discretion as is accorded the User or the Provider in estimating loss to buildings from earthquakes. The
principles should also be used in judging whether a User or Provider has conducted an appropriate assessment and estimation of
earthquake loss to a building.
4.2.1 Uncertainty Not Eliminated—No estimate can wholly eliminate uncertainty regarding damage resulting from actual
earthquakes. The successive levels of investigation described in this Guide are intended to reduce, but not eliminate, uncertainty
regarding the estimation of damage. This Guide acknowledges the reasonable limits of time and cost related to a selected level of
assessment.
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4.2.2 Not Exhaustive—There is a point at which the cost to gather information outweighs the usefulness of the information and,
in fact, may be detrimental to the orderly completion of transactions within the resources available to support the investigation.
This Guide identifies and suggests that a balance be sought between the competing goals of limiting the costs and time demands
versus limiting the resulting uncertainty regarding unknown conditions or information by acquiring as much information as
possible.
NOTE 2—Appropriate due diligence according to this Guide is not to be construed as technically exhaustive. There is a point at which the cost of
information obtained or the time required to conduct the seismic risk assessment may outweigh the usefulness of the information and, in fact, may be
a material detriment to the orderly and timely completion of a commercial real estate transaction. It is the intent of this Guide to attempt to identify a
balance between limiting the costs and time demands inherent in performing a seismic risk assessment and reducing the uncertainty about unknown
physical deficiencies resulting from completing additional inquiry.
4.2.3 Level of Investigation—Not every property warrants the same level of investigation. Consistent with good commercial or
customary practice, choosing the appropriate level of investigation is guided by the type and age of buildings subject to assessment,
the resources and time available, the anticipated severity of shaking, the expertise and risk tolerance of the User, and the
information developed during the course of the investigation.
4.3 Subsequent Use of Seismic Risk Assessments—This guide recognizes that assessments of buildings prepared for specified
levels of investigation and performed on the basis of the approaches discussed herein may include information that subsequent
Users will want to use to avoid undertaking duplicative investigations. Consequently, this guide describes procedures to assist
subsequent Users in determining how appropriate it would be to use these results. Usage of prior reports is based on the following
principles that should be adhered to in addition to the specific procedures set forth in this guide.
4.3.1 Comparability—An estimate of loss to buildings from earthquakes is not to deemed as inappropriate merely because it did
not identify all potentially vulnerable areas in connection with a building or a group of buildings. Seismic risk assessments must
be evaluated based on the reasonableness of judgments made at the time and under the circumstances in which they were made.
The result of any subsequent seismic risk assessments performed to similar parameters should not be considered as valid standards
to judge the appropriateness of any prior seismic risk assessment based on hindsight, new information, use of developing
technology or analytical techniques, or other factors.
4.3.2 Use of Prior Information—Users and Providers may use information in prior reports that meet or exceed the requirements
of this guide for specified levels of investigation and then only provided that the specific procedures set forth in the guide were
met, including the qualification of the Provider.
4.3.3 Prior Assessment Meets or Exceeds—A prior seismic risk assessment report prepared for specified levels of investigation
may be used in its entirety, without regard to specific procedures set forth in this guide, if in the judgment of the Provider, the prior
report was prepared for specified levels of investigation meeting or exceeding the requirements of this Guide and the conditions
of the building(s) and the seismic hazards affecting the site are not likely to have changed materially since the prior report was
prepared. In making this judgment, the Provider should consider the types of building construction assessed in the report, any new
information related to the behavior of that specific building construction type in recent earthquakes, as well as current
understanding of the site conditions.
4.3.4 Current Investigation—Prior seismic risk assessments should not be used without current investigation of conditions likely
to affect the current seismic risk assessment. Likely conditions include the current level of knowledge on and experience with
building constructions of particular types in recent earthquakes, as well as, current understanding of the site conditions that differ
from those in existence when the prior report was prepared.
4.3.5 Actual Knowledge Exception—If the User or Provider has actual knowledge that the information being used from a prior
seismic risk assessment report is not accurate or is suspected of being inaccurate, then such information from a prior report should
not be used.
4.4 When a new seismic risk assessment is performed for the same User that is consistent with this guide and has a higher level
of investigation than a prior investigation, then the new investigation should supersede the former one.
5. Assessment Methodology and Approach
5.1 Minimum Requirements:
5.1.1 Seismic risk assessments may be performed for an individual building or a group of buildings.
5.1.2 At the minimum, a seismic risk assessment should include an assessment of building stability (BS, Section 8) and site
stability (SS, Section 9). It may also include a building damageability (BD, Section 10), contents damageability (C, Section 11),
and/or business interruption (B, Section 12) assessment, or any combination of these.
5.1.3 An earthquake ground motion assessment (Section 7) should be conducted in conjunction with all seismic risk
assessments.
5.1.4 The User shall select any level of investigation for these assessments (Levels 0 through 3).
5.1.5 The building damageability portion of the assessment (Section 10) may report a SL, where the specific scenario and the
statistical measure reported or the probability of exceedance are given, or a PL with specified probability of exceedance and time
period, or both.
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5.1.6 The contents damageability (Section 11) and business interruption (Section 12) portions of the assessment should be
reported on the basis of a scenario loss approach.
5.1.7 Retrofit—In some cases, information on retrofitting the building may be requested by the User under specified conditions,
typically instability or damage exceeding a threshold value. In such cases, recommendations should be developed for modifications
of the building’s structural or non-structural systems, or both, including members and connections, aimed at the assessed
conditions. The required assessment should be performed for both the building in its existing condition and for the retrofitted
building condition(s), assuming the retrofit is completed as recommended with good professional practice.
5.1.8 The use of any interactive computer assessment tools developed specifically to assess the earthquake loss and requiring
only general information about the building and site (for example, structure type) should be limited to Level 0 (screening level)
assessments.
5.2 Level of Investigation:
5.2.1 Seismic risk assessments may consider varying degrees of assessment of a building or buildings from Level 0 to Level
3.
5.2.2 Four levels of investigation are described (Level 0 through Level 3), except for the assessment of ground motion for which
there are three levels (Level 0 through Level 2).
5.2.3 Level 0 is a screening investigation, while Level 3 is a highly detailed technical investigation. Levels 1 and 2 are
intermediate between these two.
5.2.4 The selection of the level of the investigations performed should be guided by the expected level of uncertainty in the
result that is acceptable to the User. The lower the tolerance for uncertainty, the higher the Level of investigation should be. The
higher the seismic hazard of the region in which the building(s) is located, the higher the level of assessment should be, all other
things being equal.
5.3 Seismic Risk Assessment for Multiple Buildings:
5.3.1 Where projects consist of multiple buildings or building structural units (sections) where earthquake impacts are
independent of each other, one or more of the following should be presented in the building loss assessment:
5.3.1.1 Building loss results for each individual building or building sections, in addition to those of the group. These results
may be expressed as an expected, mean, range, or statistic, for example, a value with 10 % probability of exceedance;
5.3.1.2 Mean and standard deviation of loss for each building or building section for selected specific events, or for the ground
motion probability distribution at the site(s);
5.3.1.3 How the individual building results are combined requires statistically valid approach to provide the SL or PL values
for the group of buildings, whether geographically dispersed or not.a group of buildings must be determined using a statistically
valid approach, including weighting of the contribution statistics by the relative replacement values for each element of the group.
5.3.1.4 Aggregate PL’s and SL’s for multiple buildings, whether geographically-dispersed or not, shall be weighted in
accordance with their respective relative replacement costs as well as those for each and every individual building. Straight
averaging or weighting based upon building area of individual PL’s and SL’s when expressed upon a percentage basis, is not
acceptable.a group of buildings must be determined in a manner that is consistent with the assumptions of the damage statistics
model used. If the individual buildings are co-located and are subject to earthquake ground motions of the same intensity
(consistent with the statistical distribution of the damage model), then conventional statistical sampling methods can be applied
to determine aggregate damage statistics. If they are not, which will be typical for geographically dispersed groups, then more
detailed models that reflect the sources of uncertainty for sources an
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