IEC 60721-2-6:2022

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
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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

– 2 – IEC 60721-2-6:2022 © IEC 2022
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

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –

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

FOREWORD
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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;

– 4 – IEC 60721-2-6:2022 © IEC 2022
d) the earthquake zone map, which was not usable in practice, is replaced by an annex giving
information about how to retrieve con
...