SIST EN IEC 60721-2-6:2023

Classification of environmental conditions. Part 2-6: Environmental conditions appearing in nature - Earthquake vibration and shock (IEC 60721-2-6:2022)

This part of IEC 60721 deals with environmental conditions appearing in nature related to earthquake vibrations and shocks.
Its object is to define some fundamental properties and quantities for characterization of earthquakes as background material for the severities to which products are liable to be exposed during storage and use. Accelerations given are for ground surface conditions only.
Conditions related to structures are referred to but restricted to general case descriptions.

Klassifizierung von Umgebungsbedingungen - Teil 2-6: Natürliche Einflüsse - Seismische Einflüsse (IEC 60721-2-6:2022)

Classification des conditions d'environnement. Partie 2-6: Conditions d'environnement présentes dans la nature. Vibrations et chocs sismiques (IEC 60721-2-6:2022)

L'IEC 60721-2-6:2022 traite des conditions d'environnement présentes dans la nature et qui sont liées à des vibrations et des chocs sismiques.
Elle a pour objet de définir des propriétés fondamentales et des grandeurs pour la caractérisation des séismes comme base pour les sévérités auxquelles les matériels sont susceptibles d'être exposés durant leur stockage et leur utilisation. Les accélérations données concernent uniquement les conditions à la surface du sol. Les conditions relatives aux structures sont mentionnées, mais leurs descriptions sont limitées aux cas généraux.
Cette deuxième édition annule et remplace la première édition parue en 1990. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:

   
1. le principal objectif de la présente révision est de classer dans un nombre limité de classes le niveau d'activité sismique de la zone où le matériel est susceptible d'être installé;

   
2. la corrélation entre les échelles d'intensité, les échelles de magnitude et l'accélération crête du sol a été supprimée en raison de l'incertitude scientifique qui existe pour la définir de manière rigoureuse;

   
3. des échelles mises à jour sont données pour l'intensité et pour la magnitude;

   
4. la carte des zones de séismes, qui n'était pas utilisable en pratique, a été remplacée par une annexe qui fournit des informations qui permettent d'obtenir une répartition cohérente de l'accélération crête du sol dans le monde entier;

   
5. en ce qui concerne l’identification de l'accélération sismique crête du sol de la zone où le matériel est susceptible d'être installé, l’utilisateur est informé que des normes et des lois nationales peuvent s’appliquer.

Klasifikacija okoljskih pogojev - 2-6. del: Okoljski pogoji v naravi - Vibracije in potresni sunki (IEC 60721-2-6:2022)

Ta del standarda IEC 60721 obravnava okoljske pogoje, ki se pojavljajo v naravi in so povezani s potresnimi tresljaji in udarci.
Njegov namen je določiti nekatere osnovne lastnosti in količine za karakterizacijo potresov kot temeljno gradivo za resnosti, ki so jim lahko izpostavljeni proizvodi med hrambo in uporabo. Navedeni pospeški veljajo samo za razmere na talnih površinah.
Navedeni so pogoji, povezani s strukturami, vendar so omejeni na splošne opise primerov.

General Information

• Status: Published
• Publication Date: 28-Feb-2023
• ICS: 19.040 - Environmental testing
• Technical Committee: I09 - Imaginarni 09
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 31-Jan-2023
• Due Date: 07-Apr-2023
• Completion Date: 01-Mar-2023
• Ref Project: EN IEC 60721-2-6:2023 - Classification of environmental conditions - Part 2-6: Environmental conditions appearing in nature - Earthquake vibration and shock

Relations

• Revised: SIST HD 478.2.6 S1:2002 - Classification of environmental conditions -- Part 2: Environmental conditions appearing in nature -- Earthquake vibration and shock
• Effective Date: 08-Dec-2020

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN IEC 60721-2-6:2023
01-april-2023
Klasifikacija okoljskih pogojev - 2-6. del: Okoljski pogoji v naravi - Vibracije in
potresni sunki (IEC 60721-2-6:2022)
Classification of environmental conditions. Part 2-6: Environmental conditions appearing
in nature - Earthquake vibration and shock (IEC 60721-2-6:2022)
Klassifizierung von Umgebungsbedingungen - Teil 2-6: Natürliche Einflüsse -
Seismische Einflüsse (IEC 60721-2-6:2022)
Classification des conditions d'environnement. Partie 2-6: Conditions d'environnement
présentes dans la nature. Vibrations et chocs sismiques (IEC 60721-2-6:2022)
Ta slovenski standard je istoveten z: EN IEC 60721-2-6:2023
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
SIST EN IEC 60721-2-6:2023 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 60721-2-6:2023


EUROPEAN STANDARD EN IEC 60721-2-6

NORME EUROPÉENNE

EUROPÄISCHE NORM January 2023
ICS 19.040 Supersedes HD 478.2.6 S1:1993
English Version
Classification of environmental conditions - Part 2-6:
Environmental conditions appearing in nature - Earthquake
vibration and shock
(IEC 60721-2-6:2022)
Classification des conditions d'environnement. Partie 2-6: Klassifizierung von Umgebungsbedingungen - Teil 2-6:
Conditions d'environnement présentes dans la nature - Natürliche Einflüsse - Seismische Einflüsse
Vibrations et chocs sismiques (IEC 60721-2-6:2022)
(IEC 60721-2-6:2022)
This European Standard was approved by CENELEC on 2023-01-19. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 60721-2-6:2023 E

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SIST EN IEC 60721-2-6:2023
EN IEC 60721-2-6:2023 (E)
European foreword
The text of document 104/946/FDIS, future edition 2 of IEC 60721-2-6, prepared by IEC/TC 104
"Environmental conditions, classification and methods of test" was submitted to the IEC-CENELEC
parallel vote and approved by CENELEC as EN IEC 60721-2-6:2023.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2023-10-19
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2026-01-19
document have to be withdrawn

This document supersedes HD 478.2.6 S1:1993 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60721-2-6:2022 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 60721-1 NOTE Approved as EN 60721-1
2

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SIST EN IEC 60721-2-6:2023
EN IEC 60721-2-6:2023 (E)
Annex A
(normative)

Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60068-3-3 2019 Environmental testing - Part 3-3: EN IEC 60068-3-3 2019
Supporting documentation and guidance -
Seismic test methods for equipment
ISO 2041 - Mechanical vibration, shock and condition - -
monitoring - Vocabulary

3

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IEC 60721-2-6

®


Edition 2.0 2022-12




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Classification of environmental conditions –

Part 2-6: Environmental conditions appearing in nature – Earthquake vibration

and shock



Classification des conditions d'environnement –

Partie 2-6: Conditions d'environnement présentes dans la nature – Vibrations et


chocs sismiques













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 19.040 ISBN 978-2-8322-6272-6




Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General description of earthquake . 6
4.1 General . 6
4.2 Earthquake origin and propagation . 7
4.3 Earthquake behaviour . 7
4.4 Products on foundations . 7
4.5 Products in buildings and structures . 7
5 Seismic scales . 7
5.1 Definition of intensity and magnitude . 7
5.2 Examples of intensity scales . 8
5.3 Example of magnitude scale . 9
6 Description of the seismic environment by response spectra . 10
6.1 Response spectrum . 10
6.2 Ground response spectrum . 10
6.3 Required response spectrum . 11
7 Seismic activity zone classification . 11
Annex A (informative) Example of seismic activity zones . 16
A.1 Classification criteria of US Uniform Building Code . 16
A.2 World seismic activity zones classification according to UBC . 16
Bibliography . 25

Figure 1 – Acceleration record of the Irpinia-Basilicata-Italy earthquake (1980) . 12
Figure 2 – Model for composing a response spectrum . 13
Figure 3 – Response spectrum of the Calitri record of Irpinia earthquake (1980)
(Figure 1) for 2 % damping ratio value . 14
Figure 4 – Example of required response spectrum for ground motion . 15

Table 1 – Earthquake intensity scales for some countries/regions . 8
Table 2 – European Macroseismic Scale (EMS-98) . 9
Table 3 – Moment Magnitude Scale . 10
Table 4 – Seismic activity zones . 11
Table A.1 – Seismic activity zones definition according to UBC. 16
Table A.2 – Seismic activity zones classification according to UBC . 16

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –

Part 2-6: Environmental conditions appearing in nature –
Earthquake vibration and shock

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 60721-2-6 has been prepared by IEC technical committee 104: Environmental conditions,
classification and methods of test. It is an International Standard.
This second edition cancels and replaces the first edition published in 1990. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the main aim of this revision is to classify in a limited number of classes the seismic activity
level of the zone where the equipment could be installed;
b) the correlation between intensity scales, magnitude scales and peak ground acceleration is
deleted due to the scientific uncertainty to define such a correlation in a rigorous way;
c) updated scales are given both for intensity and for magnitude;

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d) the earthquake zone map, which was not usable in practice, is replaced by an annex giving
information about how to retrieve consistent peak ground acceleration distribution all over
the world;
e) with regard to identification of the peak ground seismic acceleration of the zone, where the
equipment could be installed, the user is made aware that national standards and laws can
apply.
The text of this International Standard is based on the following documents:
Draft Report on voting
104/946/FDIS 104/952/RVD

Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
A list of all parts in the IEC 60721 series, published under the general title Classification of
environmental conditions, can be found on the IEC website.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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INTRODUCTION
This part of IEC 60721 is one of a series dealing with the following subjects:
– environmental parameters and their severities (IEC 60721-1);
– environmental conditions appearing in nature (IEC 60721-2);
– classification of groups of environmental parameters and their severities (IEC 60721-3).
This part of IEC 60721 is intended to be used as background material when selecting
appropriate severities of parameters relating to earthquakes for product application. Severities
1
given in IEC 60721-1 [1] should be applied.
More detailed information can be obtained from specialist documentation and from technical
literature, some of which is given in the bibliography.


___________
1
Numbers in square brackets refer to the Bibliography.

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CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –

Part 2-6: Environmental conditions appearing in nature –
Earthquake vibration and shock



1 Scope
This part of IEC 60721 deals with environmental conditions appearing in nature related to
earthquake vibrations and shocks.
Its object is to define some fundamental properties and quantities for characterization of
earthquakes as background material for the severities to which products are liable to be
exposed during storage and use. The accelerations given are for ground surface conditions
only. Conditions related to structures are referred to but restricted to general case descriptions.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60068-3-3:2019, Environmental testing – Part 3-3: Supporting documentation and guidance
– Seismic test methods for equipment.
ISO 2041, Mechanical vibration, shock and condition monitoring – Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60068-3-3 and
ISO 2041 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 General description of earthquake
4.1 General
Influences from earthquakes are vibrations which can be modelled as stochastic processes and
can affect products and provide stress in many ways.
This Clause 4 is intended to provide information on earthquake behaviour, and on the dynamic
performance of products during earthquakes. Numerical values given are typical and illustrative
but should not be considered as standard.

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4.2 Earthquake origin and propagation
An earthquake occurs when stresses have accumulated to such a degree that they cause the
breaking of the earth's crust. These instabilities are located in areas known as active seismic
zones, in connection with a series of geological accidents such as troughs, oceanic ridges,
mountain ranges, volcanoes, ocean trenches, tectonic faults.
The sudden breaking releases elastic deformation energy which will spread from the hypocentre
in the form of three typical basic waves with different speeds:
– longitudinal volume waves which compress and expand the rock in the propagation
direction;
– transversal waves which shear the rock by distortion, perpendicular to the propagation;
– surface waves which are a combination of the two previous ones and subject to surface limit
conditions.
4.3 Earthquake behaviour
Earthquakes produce random ground motions which are characterized by simultaneous but
statistically independent horizontal and vertical components. A moderate earthquake can
persist for 15 s to 30 s; a severe earthquake for 60 s to 120 s. In general, the strong part with
the highest ground acceleration can last up to 10 s. The typical broadband random motion has
its maximum energy over a frequency range from 1 Hz to 35 Hz, and produces more damaging
effects from 1 Hz to 10 Hz. Usually the vertical component of the ground motion is assumed to
be between 67 % and 100 % of the horizontal.
NOTE Maximum acceleration is commonly used in design to reflect earthquake "strength" at a particular site.
4.4 Products on foundations
The typical broadband spectra which describe the ground motion indicate that multiple
frequency excitation predominates. The vibration nature of the ground motion (both horizontal
and vertical) can be magnified in foundation-mounted products. For any given ground motion,
the magnification depends on the characteristic frequencies of vibration of the system (soil,
foundation and product) and on the mechanism of damping.
4.5 Products in buildings and structures
The ground motion can be filtered and amplified by intervening building structures to produce
fluctuating sinusoidal floor motions. The typical narrowband spectra which describe a building
floor motion indicate that single frequency excitation can predominate. The dynamic response
of floor-mounted products can reach an acceleration many times that of the maximum ground
acceleration, depending on the system damping and characteristic frequencies of vibration. The
magnification and bandwidth depend on the dynamic response characteristics of each building
and product structure. Products sensitive to frequencies ranging from 1 Hz to 10 Hz are most
likely to be affected.
5 Seismic scales
5.1 Definition of intensity and magnitude
In seismology, earthquakes are classified with the aid of various scales according to their
intensity or magnitude.
Intensity scales are determined empirically and classify earthquakes in degrees of intensity
according to their effects. Intensity scales are based on the observed effects of the shaking,
such as the degree to which people or animals were alarmed, and the extent and severity of
damage to different kinds of structures or natural features.

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Intensity is here considered a classification of the severity of the ground shaking on the basis
of observed effects in a limited area. Intensity scales, and the concept of intensity itself, have
been evolving through the course of the last century. From a pure hierarchical classification of
effects more and more attempts have been made to develop intensity as a rough instrument for
measuring the shaking; at least, it has been used in this sense. Intensity is descriptive of the
earthquake effects, rather than analytical in the manner of an instrumental measurement.
Magnitude is related to the amount of seismic energy released at the hypocentre of the
earthquake. It is based on the amplitude of the earthquake waves recorded on instruments
which have a common calibration. The magnitude of an earthquake is thus represented by a
single, instrumentally determined value.
Both these scales, intensity and magnitude, can roughly correspond with certain values of
ground acceleration; their use for establishing test values is limited.
The relationship between the intensity scales and the acceleration level on products can only
be approximated on account of the following factors:
– the soil or rock conditions (including water saturation);
– the proximity to the earthquake activity;
– the conditions of the structure or base of the product.
Also the relationship between the magnitude scale and the peak ground acceleration is limited
by the following effects:
– the soil or rock base at the location;
– the focal depth of the earthquake;
– the duration of the earthquake activity.
5.2 Examples of intensity scales
Table 1 provides a list of different intensity scales adopted by some countries.
Table 1 – Earthquake intensity scales for some countries/regions
Country/Region Seismic intensity scale used
China Liedu Scale (GB/T 17742-2020)
Europe European Macroseismic Scale (EMS-98)
Hong Kong, China Modified Mercalli Scale (MM)
India Medvedev-Sponheuer-Karnik Scale
Israel Medvedev-Sponheuer-Karnik Scale (MSK-64)
Japan JMA Seismic Intensity Scale
Kazakhstan Medvedev-Sponheuer-Karnik Scale (MSK-64)
Philippines PHIVOLCS Earthquake Intensity Scale (PEIS)
Russia Medvedev-Sponheuer-Karnik Scale (MSK-64)
Taiwan, China Central Weather Bureau Seismic Intensity Scale
United States Modified Mercalli Scale (MM)

The European Macroseismic Scale EMS-98 is the first seismic intensity scale designed to
encourage co-operation between engineers and seismologists, rather than being for use by
seismologists alone. It comes with a detailed manual, which includes guidelines, illustrations,
and application examples. The short form of the European Macroseismic Scale (see Table 2),
abstracted from [2], is intended to give a very simplified and generalized view of the EMS.

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Table 2 – European Macroseismic Scale (EMS-98)
EMS intensity Definition Description of typical observed effects (abstracted)
I Not felt Not felt.
II Scarcely felt Felt only by very few individual people at rest in houses.
III Weak Felt indoors by a few people. People at rest feel a swaying or
light trembling.
IV Largely observed Felt indoors by many people, outdoors by very few. A few
people are awakened. Windows, doors and dishes rattle.
V Strong Felt indoors by most, outdoors by few. Many sleeping people
awake. A few are frightened. Buildings tremble throughout.
Hanging objects swing considerably. Small objects are
shifted. Doors and windows swing open or shut.
VI Slightly damaging Many people are frightened and run outdoors. Some objects
fall. Many houses suffer slight non-structural damage like
hair-line cracks and fall of small pieces of plaster.
VII Damaging Most people are frightened and run outdoors. Furniture is
shifted and objects fall from shelves in large numbers. Many
well built ordinary buildings suffer moderate damage: small
cracks in walls, fall of plaster, parts of chimneys fall down;
older buildings can show large cracks in walls and failure of
fill-in walls.
VIII Heavily damaging Many people find it difficult to stand. Many houses have large
cracks in walls. A few well built ordinary buildings show
serious failure of walls, while weak older structures can
collapse.
IX Destructive General panic. Many weak constructions collapse. Even well
built ordinary buildings show very heavy damage: serious
failure of walls and partial structural failure.
X Very destructive Many ordinary well built buildings collapse.
XI Devastating Most ordinary well built buildings collapse, even some with
good earthquake resistant design are destroyed.
XII Completely devastating Almost all buildings are destroyed.

5.3 Example of magnitude scale
The Moment Magnitude Scale (MMS; denoted explicitly by M ) is a measure of an earthquake’s
w
magnitude, size or strength, based on its seismic moment, which is a measure of the work done
by the earthquake. The Moment Magnitude Scale (M ) is considered the authoritative
w
magnitude scale for ranking earthquakes by size. Caltech seismologist Hiroo Kanamori [3] using
an approximate relation between radiated energy and seismic moment approximated M by
w
M = (log M − 9,045)/1,5
w o
where
M = seismic moment is a measure of the work accomplished by the faulting of an earthquake;
o
it is measured in the units of newton metres (Nm) or joules.
An approximate indication of the relationship between seismic moment and the Moment
Magnitude Scale is given in Table 3.

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Table 3 – Moment Magnitude Scale
M M
w o
J
9
0
1,11 × 10
10
1
3,51 × 10
12
2
1,11 × 10
13
3
3,51 × 10
15
4
1,11 × 10
16
5
3,51 × 10
18
6
1,11 × 10
19
7
3,51 × 10
21
8
1,11 × 10
22
9
3,51 × 10
24
10
1,11 × 10

6 Description of the seismic environment by response spectra
6.1 Response spectrum
A commonly accepted design description of the seismic environment specially for testing
purposes is the use of response spectra. In a response spectrum the maximum absolute value
...