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PROBABILISTIC SEISMIC HAZARD ANALYSIS IN TEHRAN
AND ADJACENT AREA
BY
NOUSHIN NARAGHI ARAGHI
Thesis submitted in fulfillment of the requirements for the degree of
Doctor of Philosophy
JANUARY 2015
ii
ACKNOWLEDGEMENTS
I would like to acknowledge University Sains Malayisa for giving me the
opportunity to further my study. I would like to express my deep gratitude to
my supervisors Dr. Syed Mustafizur Rahman and Prof. Dr. Mohd Nawawi Mohd
Nordin for their continuous support and guidance.
I am thankful to Dr. Rosli Saad and Dr. Ali Beitollahi and BHRC (Building and
Housing Research Center).
Sincere thanks are extended to Professor Andrzej Kijko at University of Pretoria
Natural Hazard Centre and Dr Sepideh Karimiparidari for the insightful discussions
about this project and their guidance in my research in the phase of the hazard
computation.
A special thank to Mr Hadi Jarrahi for helping with EZFRISK and I would like to
thank to all my friends, especially Miss Samieh Joneidi who is more than a friend but
a sister.
I would like to express my deep gratitude to my family. A special thank to my
mother and my father, because they never had doubts about me, even when I had.
Last but not least, my sincere gratitude to my husband, for his love, support and
enormous patience through the study period.
iii
TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS ii
LIST OF TABLES viii
LIST OF FIGURES x
LIST OF SYMBOLS xiii
LIST OF ABBREVIATION xiv
LIST OF PUBLICATIONS xv
ABSTRAK xvi
ABSTRACT xviii
CHAPTER 1: INTRODUCTION 1
1.1 General background 1
1.2 Natural hazards 2
1.3 Earthquake hazards 3
1.4 Seismic hazards and risks of study area 4
1.5 Tectonic Framework 6
1.6 Geology of the Study area 8
1.7 Problem statement 11
1.8 Objective of thesis 12
1.9 Significances and novelties of the study 13
1.10 Thesis Organization 13
CHAPTER 2 : LITERATURE REVIEW 15
2.1 Introduction 15
2.2 Deterministic seismic hazard analysis (DSHA) 16
2.3 Probabilistic seismic hazard analysis (PSHA) 17
2.4 Previous work 21
CHAPTER 3 : METHODOLOGY 29
3.1 Introduction 29
3.2 Earthquake Catalogue of Iran 30
3.2.1 Utilization different parts of catalogue with different 31
magnitude threshold
3.2.2 The Pre-Historical and Historical events 33
3.2.3 Completeness of historical seismic data 33
3.2.4 Reliability and accuracy of historic seismic data 33
iv
3.2.5 Macroseismic epicentral location and quality criteria 34
3.2.6 Sources for the compilation of the comprehensive catalogue 37
3.2.6.1 National agencies 37
3.2.6.2 Global Agencies 37
3.2.7 Removal of duplicate events 39
3.2.8 General features of the catalogue 41
3.2.9 Estimation of moment magnitude 41
3.2.10 Orthogonal Regression 42
3.2.11 Homogenizing Earthquake Magnitude Scales 43
3.2.11.1 The conversion of body wave magnitude ( ) 43
to moment magnitude ( )
3.2.11.2 The conversion of surface wave magnitude ( ) 44
to moment magnitude ( )
3.2.11.3 The conversion of local magnitude ( ) and 46
Nuttli magnitude ( to moment magnitude ( )
3.2.12 Declustering process and Elimination of foreshocks and 49
aftershocks
3.2.13 The Analysis of completeness 50
3.3 Seismotectonic framework 54
3.3.1 The Alborz seismotectonic province 55
3.3.2 The central Iran seismotectonic province 57
3.3.4 Seismotectonic framework in study area 57
3.3.5 Focal Mechanism in the study area 58
3.3.6 Seismotectonic sources in the study area 59
3.3.6.1 Fault sources 60
3.3.6.2 Area sources 60
3.4 Fault sources in the study area 61
3.4.1 Mosha fault 62
3.4.2 Kahrizak fault 62
3.4.3 Khazar fault 63
3.4.4 North Alborz fault 63
3.4.5 Kashchal fault 63
3.4.6 Kandevan fault 63
3.4.7 North Qazvin reverse fault 64
v
3.4.8 Abyek fault 64
3.4.9 Taleqan fault 64
3.4.10 Firuzkuh fault 64
3.4.11 Astaneh fault 65
3.4.12 Chashm fault 65
3.4.13 North Tehran fault 65
3.4.14 Ipak fault 66
3.4.15 Eshtehard fault 66
3.4.16 Robatkarim fault 66
3.4.17 Band-e-siah fault 66
3.4.18 Siahkuh fault 66
3.4.19 North Ray fault 67
3.4.20 Parchin fault 67
3.4.21 Pishva fault 67
3.4.22 Garmsar fault 67
3.4.23 Kushk-e-Nosrat fault 67
3.4.24 Indes fault 67
3.4.25 Qom-Zefreh fault 68
3.5 Computation of maximum moment magnitude for each fault 68
3.6 Evaluation of seismic parameters 73
3.6.1 Seismicity parameters for Azerbaijan-Alborz and central Iran 77
3.7 The ground motion attenuation relations 85
3.8 Ground Motion Prediction Equations 86
3.8.1 Campbell–Bozorgnia NGA model 87
3.8.2 Boore–Atkinson NGA model (2008) 90
3.8.3 Chiou-Youngs NGA model (2008) 94
3.8.4 Abrahamson-Silva model (1997) 96
3.8.5 Boore, Joyner and Fumal model(1997) 98
3.8.6 Campbell-Bozorgnia model(2003) 99
3.8.7 Sadigh et al. model(1997) 101
3.9 Proposed technique model for seismic hazard assessment 102
3.10 Theorical background for EZFRISK software 103
3.11 Analysis of Seismic Hazard from Fault Sources 104
vi
3.11.1 The source parameters for the active crustal faults 104
3.11.1.1 Maximum and minimum magnitude 105
3.11.1.2 Rate 105
3.11.1.3 Fault rupture type 105
3.11.1.4 Magnitude recurrence relationship 105
3.11.1.5 Fault Coordinates 106
3.11.1.6 Fault Rapture 107
3.12 Analysis of Seismic Hazard from Area Sources 109
3.12.1 The source parameters for Area Sources 110
3.12.1.1 Maximum and minimum magnitude 110
3.12.1.2 Recurrence relationship 110
3.12.1.3 Background source coordinate 111
3.12.1.4 Rupture Length 112
3.13 Hazard Analysis modeling of the study area 112
3.14 Seismic Hazard Analysis Modeling Assumption 113
3.15 Multi-site Analysis 113
CHAPTER4 : RESULTS AND DISCUSSION 116
4.1 Introduction 116
4.2 Magnitude conversion relations and comparison with the available results 116
4.3 Single site results 120
4.3.1 Site 1 Results for Tehran 122
4.3.2 Site 2 Results for Karaj 128
4.3.3 Site 3 Results for Rey 129
4.3.4 Site 4 Results for Qom 130
4.3.5 Site 5 Results for Qazvin 132
4.3.6 Site 6 Results for Garmsar 133
4.3.7 Site 7 Results for Sari 135
4.3.8 Site 8 Results for Semnan 136
4.4 Hazard map results 138
CHAPTER 5 : CONCLUSION AND RECOMMENDATION 151
5.1 Conclusion 151
5.2 Recommendation 153
vii
REFERENCES 154
APPENDIX A 168
The earthquake catalogue for Azerbayjan-Alborz area 168
APPENDIX B 187
The earthquake catalogue for Central Iran area 187
APPENDIX C 193
Attenuation coefficient 193
APPENDIX D 210
Soil types and shear wave velocity 210
viii
LIST OF TABLES
Page
Table 3.1 Pre-historical and historical data for study area 36
Table 3.2 Priority to choose magnitude and location from international 40
and national databases based on magnitude, location and intensity
Table 3.3 Spatial and temporal parameters for declustering algorithm 50
Table 3.4 Magnitude of completeness for different periods in 52
Azerbaijan Alborz seimotectonic zone
Table 3.5 Maximum moment magnitude was calculated from relations 70
Table 3.6 Seismic parameters for major faults in study area. The Khazar 72 and North Alborz faults are sub-divided into two sub-faults which are
modeled as independent sources
Table 3.7 Seismicity parameters for two seismotectonic zones 78
Table 3.8 Mean activity rate ( ), Return period ( ), annual probability of 82
exceedance, probability of exceedance for 1, 50, 100 and 1000
years for Azerbaijan-Alborz seismotectonic province
Table 3.9 Mean activity rate ( , Return period ( ), annual probability of 84
exceedance, probability of exceedance for 1, 50, 100 and 1000
years for Central Iran seismotectonic province
Table 3.10 Essential rupture length parameters as input for software 108
Table 4.1 selected sites and their coordinates 120
Table 4.2 The uniform hazard spectra values for site 1 for 475- year return 122
period
Table 4.3 The uniform hazard spectra values for site 1 for 975- year return 122
period
Table 4.4 The uniform hazard spectra values for site 1 for 2475- year return 123
period
Table 4.5 The uniform hazard spectra values for site 2 for 475-year return 128
period
Table 4.6 The uniform hazard spectra values for site 2 for 975-year return 128
period
Table 4.7 The uniform hazard spectra values for site 2 for 2475-year return 129
period
Table 4.8 The uniform hazard spectra values for site 3 for 475-year return 129
period
ix
Table 4.9 The uniform hazard spectra values for site 3 for 975-year return 130
period
Table 4.10 The uniform hazard spectra values for site 3 for 2475-year return 130
period
Table 4.11 The uniform hazard spectra values for site 4 for 475-year return 131
period
Table 4.12 The uniform hazard spectra values for site 4 for 975-year return 131
period
Table 4.13 The uniform hazard spectra values for site 4 for 2475-year return 132
period
Table 4.14 The uniform hazard spectra values for site 5 for 475-year return 132
period
Table 4.15 The uniform hazard spectra values for site 5 for 975-year return 133
period
Table 4.16 The uniform hazard spectra values site 5 for 2475-year return 133
period
Table 4.17 The uniform hazard spectra values for site 6 for 975-year return 134
period
Table 4.18 The uniform hazard spectra values for site 6 for 2475-year return 134
period
Table 4.19 The uniform hazard spectra values for site 6 for 2475-year return 135
period
Table 4.20 The uniform hazard spectra values for site 7 for 475-year return 135
period
Table 4.21 The uniform hazard spectra values for site 7 for 975-year return 136
period
Table 4.22 The uniform hazard spectra values for site 7 for 2475-year return 136
period
Table 4.23 The uniform hazard spectra values for site 8 for 475-year return 137
period
Table 4.24 The uniform hazard spectra values for site 8 for 975-year return 137
period
Table 4.25 The uniform hazard spectra values for site 8 for 975-year return 138
period
Table 4.26 The design base acceleration ratio for various region 145
x
LIST OF FIGURES
Page
Figure 1.1 Map of Iran. Study area is inside the box 6
Figure 1.2 Seismotectonics of the Middle East and vicinity (Walter, 2002) 7
Figure 1.3 Structural zones of Iran (Stocklin, 1968) 10
Figure 2.1 Steps in Deterministic Seismic Hazard Analysis. 17
Figure 2.2 Steps in Probabilistic Seismic Hazard Analysis 18
Figure 2.3 Comparison Multiple faults in PSHA and DSHA 21
Figure 3.1 The flowchart of the Methodology used for the study 30
Figure 3.2 Illustration of data to obtain basic seismic hazard parameters for 32
the selected area
Figure 3.3 Available catalouges used for different time periods 38
Figure 3.4 The regression between moment magnitude and body wave 44
Figure 3.5 The regression between moment magnitude and surface wave 45
Figure 3.6 The regression between moment magnitude and surface wave 46
erugiF3.7 The regression between moment magnitude and local magnitude 47
Figure 3.8 The regression between moment magnitude and Nuttli magnitude 48
Figure 3.9 Number of earthquake events with time 51
Figure 3.10 Magnitude of events in different period of time 51
Figure 3.11 Frequency of the earthquakes occurred from 1900 to 1960 for 53
Azerbaijan-Alborz
Figure 3.12 Frequency of the earthquakes occurred from 1961 to 2013 for 53
Azerbaijan-Alborz
Figure 3.13 Frequency of the earthquakes occurred from 1900 to 2013 for 54
central Iran
Figure 3.14 Seismotectonic model for the Iranian plateau 56
Figure 3.15 Schematic Diagram of a focal mechanism (USGS, 2012) 59
Figure 3.16 Fault map of Tehran Region 61
Figure 3.17 The Guthenburg-Richter magnitude frequency relationship 76
Figure 3.18 Annual probability of exceedance with magnitude in 78
Azerbaijan-Alborz zone
Figure 3.19 Return period of earthquakes with magnitude in Azerbaijan– 79
Alborz zone
Figure 3.20 Probability of exceedance with magnitude in Azerbaijan–Alborz 79
zone in different periods (50, 100 and 1000 years)
xi
Figure 3.21 Annual probability of exceedance with magnitude in Central Iran 79
zone
Figure 3.22 Return period of earthquakes with magnitude in Central Iran zone 80
Figure 3.23 Probability of exceedance with magnitude in Central Iran zone in 81
different periods (50, 100 and 1000 years)
Figure 3.24 Definition of variable 96
Figure 3.25 The graphical representation of fault modeling in EZ-FRISK 107
Figure 3.26 Fault source three definitions of distance R 109
Figure 3.28 Background source coordinate for Azerbayjan-Alborz 111
seismotectonic province
Figure 3.27 Area source modeling in EZFRISK 111
Figure 3.29 Background source coordinate for Central Iran seismotectonic 112
province
Figure 3.30 Shear wave velocity map in study area 114
Figure 3.31 Distribution of site points in study area 115
Figure 4.1 Result comparison of this study with moment magnitude ( ) 117
versus body wave magnitude ( ) obtained by Scordilis (2006)
and Karimiparidari et al. (2013)
Figure 4.2 Result comparison of this study with moment magnitude ( 118
versus surface wave magnitude( )obtained by Scordilis (2006)
and Karimiparidari et al. (2013) for
Figure 4.3 Result comparison of this study with moment magnitude ( 118
versus surface wave magnitude ( ) obtained by Scordilis (2006)
and Karimiparidari et al.(2013) for
Figure 4.4 Result comparison of this study with moment magnitude 119
versus local magnitude ( obtained by Karimiparidari et al.(2013)
Figure 4.5 Result comparison of this study with moment magnitude ( ) 119
versus Nuttli magnitude ( obtained by
Karimiparidari et al. (2013)
Figure 4.6 Locations of eight test sites used in the study area 121
Figure 4.7 Mean hazard curve for the mean value of PGA for site 1 123
Figure 4.8 Total hazard curve value in site 1 (spectral period=0.2s) 124
Figure 4.9 Total hazard curve value in site 1 (spectral period=1.0s) 124
acceleration
Figure 4.10 Uniform hazard spectra, spectra periods versus spectral 125
Figure 4.11 Hazard by seismic source for PGA 126
xii
Figure 4.12 Hazard by seismic source for spectral acceleration of 0.2 s 126
Figure 4.13 Hazard by seismic source for spectral acceleration of 1.0 s 127
Figure 4.14 PGA(g) hazard map of the study region with a 475-year return 139
Figure 4.15 PGA(g) hazard map of the study region with a 975-year return 139
period.
Figure 4.16 PGA(g) hazard map of the study region with a 2475-year return 140
period
Figure 4.17 Spectral acceleration(g) (0.2s) map of the study region with a 140
475-year return period
Figure 4.18 Spectral acceleration (g)(0.2s) map of the study region with a 141
975-year return period
Figure 4.19 Spectral acceleration(g) (0.2s) map of the study region with a 141
2475-year return period
Figure 4.21 Spectral acceleration(g) (1.0s) map of the study region with a 142
975-year return period
Figure 4.20 Spectral acceleration(g) (1.0s) map of the study region with a 142
475-year return period.
Figure 4.22 Spectral acceleration(g) (1.0s) map of the study region with a 143
2475-year return period
Figure 4.23 Comparison Hamzehloo et al. (2012) and this study in peak 146
ground acceleration map for return period of 475 years
(g= 980.66 (cm/s²))
Figure 4.24 Comparison Hamzehloo et al. (2012) and this study in peak 147
ground acceleration map for return period of 2475 years
(1g= 980.66 (cm/s²))
Figure 4.25 Comparison Hamzehloo et al. (2012) and this study in spectral 148
acceleration map
Figure 4.26 Comparison Hamzehloo et al. (2012) and this study in spectral 149
acceleration map
Figure 4.27 Comparison Abdi et al. (2013) and this study in peak ground 150
acceleration
xiii
LIST OF SYMBOLS
Minimum Magnitude
Maximum Magnitude
a a-value
b b-value
Moment magnitude
Maximum moment magnitude
Body wave magnitude
Richter magnitude
Nuttli magnitude
Surface wave magnitude
Magnitude of completeness
Fault Length
Mean seismic activity rate
Largest observed magnitude
RP Return period
xiv
LIST OF ABBREVIATION
ASCE American Society for Civil Engineers
BHRC Building and Housing Research Center
CL Construction Level
DBL Design Basis Level
DSHA Deterministic Seismic Hazard Analysis
FMD Frequency Magnitude Distribution
GMPE Ground Motion Prediction Equations
GOR General Orthogonal Regression
IBC 2006 International Building Code
IIEES International Institute of Earthquake Engineering and Seismology
IRSC Iranian Seismological Center
ISC International Seismological Center
ISR Inverted Standard Least-Squares Regression
MCDL Maximum Credible Design level
MDL Maximum Design Level
NEIC National Earthquake Information Center
NGA New Generation Attenuation
OR Orthogonal Regression
PGA Peak Ground Acceleration
PGD Peak Ground Displacement
PGV Peak Ground Velocity
PHA Peak Horizontal Acceleration
PSHA Probabilistic Seismic Hazard Analysis
SA Spectral Acceleration
SR Standard Least-Squares Regression
xv
LIST OF PUBLICATIONS
Araghi, N. N., Rahman, S. M., Joneidi, S. and Saad, R. (2011). Probabilistic seismic
hazard assessment in Gilan Province of Iran. Geoscientists and Ethics for a
Sustainable Society.
Faruk, M. O., Rahman, S. M., Hashem, A, Keramat. M. and Araghi, N. N.(2012).
Group Velocity Dispersion Analysis of Meiktila Myanmar Earthquake for
Studying the Crustal Thickness, GEOS 2012, Annual International Conference on
Geological Earth Sciences, Singapore.
Araghi, N. N., Nawawi, M. and Rahman, S. M. (2013). Study seismicity parameters
of Rudbar region and seismological assessment of RudbarMnajil (Iran) earthquake
of June 1990, The third International Conference on Geotechnique,
Construction Materials and Environmental GEOMATE November 2013
Nagoya Japan.
Araghi, N. N., Nawawi, M., and Rahman, S. M. (2013). Spatial analysis of a-value
and b-value variability in Alborz.Journal of Geological Science, Vol.1 No. 2.
Araghi, N. N., Nawawi, M. and Rahman, S. M. (2014). The effect of Sumatra fault
earthquakes on west Malaysia, The forth International Conference on Geotechnique,
Construction Materials and Environmental GEOMATE, November 2014,
Brisbane, Australia .
xvi
PENILAIAN KEBARANGKALIAN BENCANA SEISMOS DI TEHRAN DAN
KAWASAN BERHAMPIRAN
ABSTRAK
Dalam kajian ini, analisis kebarangkalian Bencana Seismos (PSHA) telah dilakukan
di Tehran dan di kawasan sekitarnya. Penilaian Kebarangkalian Bahaya Seismos
(PSHA) merupakan prosedur yang sering digunakan secara meluas dalam penilaian
bencana seismos. PSHA memaparkan kebarangkalian semulajadi bencana seismos
dengan mengintegrasikan semua sumbangan magnitud gempa bumi yang
berkemungkinan serta lokasi dalam bentuk yang konsisten. Katalog gempa bumi
yang seragam adalah penting dalam penilaian bencana seismos. Dalam kajian ini,
sebuah katalog gempa bumi Tehran dan kawasan sempadannya telah dikumpulkan
dengan mengabungkan bank data antarabangsa dan tempatan. Pempiawaian katalog
dalam perihal magnitud telah dicapai dengan mengubah kesemua jenis magnitud
kepada magnitud momen dengan menggunakan kaedah regresi ortogon. Dalam
katalog baru yang disatukan, semua kejutan lanjuran dan kejutan depan telah dikesan
dan dibuang dari katalog. Kawasan kajian ini dibahagikan kepada dua kawasan
seismos berasaskan kepada rejim seismotektonik. Sumber seismos telah didefinisikan
sebagai sumber sesaran dan sumber kawasan. Parameter keseismosan dan magnitud
kelengkapan minimum telah dihitung berasingan bagi sesar-sesar dan setiap zon
seismos dalam kawasan tersebut. Empat hubungan pengecilan dan tiga hubungan
pengecilan NGA baharu telah dipilih dan diambil kira dalam kajian ini. Puncak
pecutan bumi (PGA) tidak mencukupi untuk mereka bentuk kod bangunan moden
maka PGA dengan nilai pecutan spectrum telah dianggarkan dan digunakan dalam
tempoh masa 0.2 dan 1.0 s.
xvii
Analisis bencana seismos telah dilakukan pada beberapa titik terpilih dan peta
bencana bagi puncak pecutan bumi mendatar dan pecutan spektrum (T=0.2 saat dan
T=1.0 saat) bagi jangka pulangan yang berbeza (475, 975 dan 2475 tahun) telah
dihasilkan dan dibandingkan dengan hasil yang sedia ada dalam literatur.
Peta dalam kajian ini menunjukkan tahap anggaran yang lebih tinggi puncak pecutan
bumi dan respon pecutan spektrum yang dijangka dalam pelbagai tempoh pulangan
daripada yang dihasilkan dalam kajian sebelum ini. Model baru itu dijangka
menghasilkan pengubahsuaian besar untuk kod bangunan.
xviii
PROBABILISTIC SEISMIC HAZARD ANALYSIS IN TEHRAN AND
ADJACENT AREA
ABSTRACT
In the current study, probabilistic seismic hazard assessment (PSHA) for Tehran and
adjacent area has been performed. Probabilistic seismic hazard analysis (PSHA) is
the most widely used procedure for seismic hazard assessment. PSHA displays the
probabilistic nature of seismic hazard by integrating the contributions of all possible
magnitude earthquakes and locations in a consistent manner. A uniform earthquake
catalogue is an essential tool in any seismic hazard analysis. In this study, an
earthquake catalogue of Tehran and adjacent areas was compiled by merging
international and local databanks. The standardization of the catalogue in terms of
magnitude was achieved by the conversion of all types of magnitude into moment
magnitude by using the orthogonal regression technique. In the newly compiled
catalogue, all aftershocks and foreshocks were detected and eliminated from the
catalogue. The study area is divided into two seismic regions based on their
seismotectonic regime. The seismic sources have been defined as fault sources and
area sources. The seismicity parameters and minimum magnitude of completeness
were calculated separately for the faults and each seismic zone in the area. Four
attenuation relationships and three new generation attenuation relations (NGA) have
been selected and considered for this study. Peak ground acceleration (PGA) is not
sufficient to design for the modern building codes, so PGA along with spectral
acceleration values have been estimated and used in period of 0.2 s and 1.0 s.
Seismic hazard analysis was performed in selected points and the hazard maps for
horizontal peak ground acceleration and spectral acceleration (T=0.2 sec and T=1.0
xix
sec) for different return periods (475, 975, and 2475 years) have been produced and
compared with those available in literature.
Maps in this study show higher estimate levels of peak ground acceleration and
response spectral accelerations expected in various return periods than those
produced in the earlier researches. The new model is therefore expected to result in
considerable modifications to the building code.
1
CHAPTER 1
INTRODUCTION
1.1 General background
Vulnerability due to earthquake in many places of the world is seemed to be
increasing. The number of victims and damages particularly in the developing
countries could be addressed increasing because of over population, poor
construction works and lack of useful building codes.
Iran is among the most seismically active places on the world. Over the last
number of years, many people died and encountered social and economic problems.
Iran has been host to a long series of large damaging earthquakes. There have been
roughly 126000 deaths attributed to 14 of magnitude of 7 and 51 earthquakes of 6 to
6.9 that have occurred in Iran since 1900. During this period nine cities were
destroyed. Review of historical seismic data shows that every part of the country has
been hit by major earthquakes.
For example, during the 1990 Rudbar earthquake (moment magnitude =7.3) in
northwest Iran, more than 40000 people lost their lives, more than 50000 became
homeless, nearly 100000 buildings were destroyed, three cities and 700 villages were
demolished. In December 2003 an earthquake measuring moment magnitude of 6.6
devastated the city of Bam, 1,000 kilometer southeast of Tehran 31,000 people were
killed.
2
Report on these seismic events demonstrates nearly all part of the region is being
suffered and has gone under experiences of the severe economic process and social
damages by major earthquakes.
Hence, it is important for the scientists and engineers to reduce such destructions
through scientific research and development. A useful map is used as an aid for the
sustainable development and can explain seismic hazard through the understanding
and uses of seismogenic faults, ground motions, existing building codes or any
relevant associated parameters (Gholipoor et al., 2008).
1.2 Natural hazards
Any undesirable event in any system is hazard. Natural hazard indicates the
occurrence of a natural risky event in a in a defined space and time. Natural hazards
tend to be harmful and often create damage to the physical as well as social on short
time and long-term basis because of their effects, thus hazards are the consequence
of instant changes within long-term behavior caused by minute. These hazards are
highly relevant to geomorphology while they are important parts of the Earth’s
surface dynamics (Alcantara-Ayala, 2002).
Rapid changes due to Earth system processes could rearrange the planet’s
surface in a moment with consequences for both natural systems and people’s
welfare and livelihoods (Young and Leon, 2009). Cities are definitely more
vulnerable to disasters because of the density of buildings, population, and
infrastructure. Unfortunately, many urban as well as rural dwellers live near the
coasts or active seismic faults and are subject to natural hazards like hurricanes,
landslides or earthquakes (Montoya and Masser, 2005).
3
1.3 Earthquake hazards
Earthquakes tend to be the most harmful associated with natural hazards.
Earthquake happens because of unexpected instant movement of the ground as a
result of release of elastic energy in a matter in couple of seconds. Earthquakes
happen sudden and affect large area so the impact of the event is harmful. They
could lead to huge loss of life and property and disturb important services
including sewerage systems, communication, power, water supply transportation
and many others.
Earthquakes demolish cities, towns and villages and destabilize the economy and
social structure of the region. Earthquakes lead to huge damage in lifelines,
structures and other facilities for prepared and less prepared regions in spite of
awareness and mitigation attempts. Consequently, it is essential to create plans that
could set priorities for prevention, reduction, and compensation for regions.
Government and public awareness could play fundamental role in reducing human
and financial losses due to earthquakes if decision makers know what could be done
in advance to reduce hazards (Momani, 2011).
Seismic hazard assessment research is actually important for identification of the
zones with various hazards that will help doing additional risk studies, land use
planning and updating construction codes.
The energy released by an earthquake sets many processes into action, and may
have both short-term and long-term consequences. Some of the hazards make effect
immediately, and others may not appear for days, weeks, or months after the event.
Earthquakes are associated with a wide variety of specific hazards, including primary
4
effects such as ground motion, ground breaks (or faulting), mass wasting and
liquefaction.
Secondary and tertiary hazards are indirect effects, caused by events initiated by
the earthquake. These may include explosions, tsunamis and fires caused by
interruption of pipelines utilities (Kusky and Kushy, 2008).
1.4 Seismic hazards and risks of study area
Seismic hazard analysis is the evaluation of the maximum amplitude of some
ground motion parameter (peak ground acceleration, peak ground velocity, relative
displacement, etc.) expected to occur once at a certain site or area within a particular
time span. This time span is referred to the return period, which is the reciprocal of
the annual probability of occurrence of certain amplitude (Thenhaus and Campbell,
2003).
Seismic hazard is often displayed on a ground motion hazard map, which
illustrates the regional differences in expected ground motion amplitude (typically
PGA) at a constant return period.
The growth of population, high buildings and big cities lead to the increase in
damages caused by seismic hazards. Throughout the twentieth century, huge
earthquakes have caused about 90 % of direct deaths because of buildings collapsing
(Lantada et al., 2009). Consequently, happening of great earthquakes and their
effects in different areas during the last couple of years informs us about the
necessity of hazard assessment (Mohanty and Walling, 2008). The probabilistic
earthquake hazard analysis aim to estimate the likelihood function of the study area
for any specified level of ground motion due to the cause of earthquakes from
5
potential seismic sources (Hamouda, 2011). Iran situated on the Alp-Himalayan belt
one of the seismic zones in the world where critical earthquakes have always been
happening(Ghobadi and Fereidooni, 2012).
The Iranian plateau is famous because of recent volcanic, active faults and high
surface elevation alongside the Alpied earthquake belt. Extremely high density of
active and recent faults could be observed in Iranian Plateau according to the tectonic
studies.
Tectonics information, the historical earthquakes data, fault activity, geology and
seismic source models are used for seismic hazard map based on probabilistic
seismic hazard. These maps explain the earthquake hazard of study area in the forms
of iso-acceleration contour lines, and include the probabilistic estimates of Peak
Ground Acceleration for different return periods.
The basis for all seismic hazard assessment is the investigation of seismicity or
the occurrence of earthquake in space and time (Scawthorn and Chen, 2002;
Tavakoli and Ghafory-Ashtiany, 1999).
The considered region in this research is the area including mega city of Tehran
and adjacent area covers a square limited by 34.35˚N to 37.10˚N and 49.80˚E to
53.10˚E. It covers the northern central Iranian depression in the south and the central
part of the Alborz mountain in the north (Figure1.1).
6
1.5 Tectonic Framework
The tectonic framework physically links the geologic, geodetic and
seismological data on earthquake sources and constrains geodetic models of crustal
deformation. Plate tectonic processes cause earthquake events and crustal
deformation. These processes have been going on for hundreds or millions of years
(Gholipoor et al., 2008).
Figure 1.1 Map of Iran. Study area is inside the box
7
Four major tectonic plates (Arabia, Eurasia, India and Africa) are responsible for
seismicity and tectonics in the Middle East and adjacent area (Figure 1.2). The active
deformation of the Iranian plateau, as a tectonically active part of Alpine-Himalayan
tectonic belt is effected by the Arabian–Eurasian convergence and it makes regions
with different seismotectonic features.
Figure 1.2 Seismotectonics of the Middle East and vicinity (Walter, 2002).
The early Quaternary tectonic history and the pre-Quaternary geological record
are very important in understanding the present continental deformation during
earthquakes. Iranian seismic activity is directly related to reactivation of the existing
faults and it is separated into three categories:
i. The Zagros active fold-thrust belt, where shortening along longitudinal high
angle reverse basement faults spread over the entire belt, is absorbed by
8
ductile layers of the top sedimentary cover (usually no earthquake rupture is
observed at the surface).
ii. The Central Iranian plateau, where the earthquakes are accompanied by
surface faulting along mountain-bordering reverse faults.
iii. The Makran accretionary flysch wedge where the oceanic crust of the Oman
Gulf is subducting underneath the southeastern Central Iran.
Tectonic shows movements during the late Neogene-early Quaternary and the
mechanism of the recent active fault motions explains that the Iranian plateau is a
broad zone of compression deformation. The plateau is a quite weak belt affected by
several collisional orogenic movements and is being compressed between two blocks
(Arabia and Eurasia), since 65 Million years. The compressional motion between
these blocks resulted in a continuous thickening and shortening of the continental
crust by reverse faulting and folding in a NE-SW direction. Situation of the Iranian
plateau between two impinging zones of the Arabian plate in the west and the Indian
plate in the east has provided a unique constrained convergent zone along the Alpine-
Himalayan belt (Copley and Jackson, 2006).
1.6 Geology of the Study area
Systematic geological studies in Iran started in late 1960s with the establishment
of the Geological Survey of Iran. The tectonic and structural setting of Iran in the
Alpine–Himalayan orogenic belt, and the structural evolution of Iran, has been the
focus of many studies. Using Stocklin and Nabavi (1973) was the first to publish a
tectonic map of Iran. The authors divided Iran into 10 structural zones (units) based
on certain geological features: Makran, the Lut Block, Eastern Iran, Kope Dagh,
the Alborz mountains, the Central Iran Block, the Urumieh-Dokhtar zone, the
Sanandaj-Sirjan zone, the Zagros fold belt, and the Khuzestan plain. The
9
boundaries of these units are usually marked by faults or in some cases
(mainly tectonic) depressions. This structural division remained a reference for
Iranian geologists for almost three decades (Figure 1.3).
New observations and findings require a revision to this structural scheme.
Following this structural division by Stocklin and Nabavi, some other structural
divisions were presented that are cited in following section related to Central Iran.
These newer structural schemes are mostly derived and inspired by the very first
structural division presented by Stocklin(1968). In recent years, new interpretations
and models have been offered regarding the geological setting of Iran (Nabavi, 1976;
Eftekharnezhad, 1980; Nogol-e-Sadat, 1993; Alavi, 1996; Aghanabati, 2004).
Northern region of Tehran province is a part of Alborz mountains while southern
Tehran is located in central Iran plain so Tehran province belongs to Alborz and
central Iran structural zones. The boundary between these zones matches on northern
Tehran thrust fault. The oldest stratigraphic units of Tehran province include a late
Precambrian to mid Triassic platform sequence which emprise several geologic
formations and sedimentary unconformities indicating land-forming movements
during late Precambrian to mid Triassic time. These units outcrop specially on
upriver regions of Karaj River.
10
Figure 1.3 Structural zones of Iran (Stocklin, 1968)
11
1.7 Problem statement
People have been experiencing numerous catastrophic earthquakes all around the
world. As there are no reliable means to predict the timing of these
earthquakes, engineers focus on preventing significant earthquake loss by
designing earthquake-resistant new structures and seismically mitigating existing
structures based on proper seismic hazard analysis.
Major earthquakes in Iran have motivated Iranian scientists to map and study the
seismic hazard and enhance existing building codes. The study of earthquake hazard
plays an important role in the sustainable development countries like Iran, where
earthquakes have occurred repeatedly.
Most researchers have concluded their seismic hazard analyses by reporting the
PGA value of Iran. This value will be very useful once the analysis of structures
becomes based on local Building codes for Iran. However, the analysis of a structure
based on International Building Code (IBC) 2003 or IBC 2006 is not possible using
PGA alone; instead, spectral acceleration values are required for a return period of
2500 years.
Within the scope of the literature review done for this study, it was established
that only Gholipour et al. (2008), Hamzeloo et al. (2012) and Abdi et al. (2013) had
applied estimation of spectral acceleration along with peak ground acceleration. In
this study, we perform a seismic hazard analysis of Tehran and the surrounding areas
and suggest spectral acceleration values in line with ASCE (American Society for
Civil Engineers) and IBC 2006 (International Building Code of 2006) and improve
the results by considering fault slip rates along with fault activity rate and using new
generation attenuation relations .
12
Improve the accuracy and quality of existing data is a knowledge gap to be filled
in this study. However, establishment of a local relation for converting magnitudes
instead of global relations is also considered in this study, Hence, a new but a simple
relation is developed for this study.
1.8 Objective of thesis
The general approach to seismic hazard evaluation is usually directed towards
reducing the uncertainties at various stages of the research process by collecting a
sufficient amount of reliable and relevant data. In this study, the available
geophysical, geological, seismological and geodetic characteristics of the project area
are evaluated. The database should be sufficient to determine the strong ground
motion at the project area.
In summary the objectives of this research are:
i. To develop and update earthquake data to compile a comprehensive
earthquake catalogue of the region and standardize the event catalogue in
terms of magnitude to generate a uniform catalogue with moment
magnitudes.
ii. To develop and validate data for faults and produce the existing fault
mechanism and an effective fault map for the region for developing a
comprehensive seismicity of the study area and calculating seismic
parameters using available earthquake catalogues.
iii. To investigate the New Generation Attenuation (NGA) functions using the
Iranian recorded ground motions to verify its applicability for use in the
hazard analysis of the research for the study area and produce Peak Ground
13
Acceleration (PGA) and Spectral acceleration(SA) for the entire study area
in different return periods.
iv. To develop new seismic hazard maps for the study area.
1.9 Significances and novelties of the study
The uniqueness and novelties of this study are as follows:
i. The study adopted a novel approach of homogenizing the earthquake
magnitudes for this area.
ii. The study will be the first to build seismic hazard map of the area based on
combination of new generation attenuation and the old attenuation relations
considering the fault slip rate along with the activity rate to generate new
hazard maps based on International building codes.
iii. The study improved the accuracy and quality of existing data.
1.10 Thesis Organization
Generally, the content of this thesis is as organized in five chapters. The
components of each chapter are briefly discussed as follows:
Chapter1 presents the introduction of the study. This chapter is discussed under
background of study area, problem statement, research objectives and location of the
study area.
Chapter 2 is devoted to review the early studies using the two approaches of
seismic hazard analysis (Deterministic and Probabilistic) However, only study on
probabilistic seismic hazard is to be highlighted.
14
Chapter 3 deals with the methodologies adopted for the study and discuss
compilation of the earthquake catalogue, by merging information from different
international and local sources and conversion all magnitudes into moment
magnitude. Processing of the data, which includes removing of duplicate events,
homogenizing, declustering, and calculating magnitude of completeness has been
carried out. The next part of this chapter summarizes geological and seismotectonic
setting of the study area and includes the study of the active faults in this area and
calculates maximum moment magnitude related to each fault. The last part of this
chapter describes seismicity assessments, calculates seismic hazard parameters
separately for each seismotectonic zone and deals with the selection of ground-
motion prediction equations and explains Four ground motion equations and three
new generation attenuation relations appropriate for this region. The final part of this
chapter proposes model for seismic hazard assessment and illustrates the outline of
the seismic hazard assessment methodology applied in the current study by using the
EZ-FRISK.
Chapter 4 allows showing the results of probabilistic seismic hazard analysis in
terms of maps and tables for PGA and spectral acceleration in different return
periods along with comprehensive discussions.
Finally, Chapter 5 makes conclusions of the current research and contains the
outcome of the hazard assessment and including recommendations for future
research.
15
Chapter 2 CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
Seismic hazard is related to any physical phenomena associated with an
earthquake (ground motion, ground failure, liquefaction, and tsunami) and their
effects on land, man-made structures and economic systems that have the
potential to produce a loss (Kijko, 2011a). Seismic hazard analysis is a critical part of
the development of design ground motions (Zhao, 2005).
There are two approaches for the seismic hazard analysis, Deterministic Seismic
Hazard Analysis (DSHA) and Probabilistic Seismic Hazard Analysis (PSHA). Both
probabilistic and deterministic methods have a role in seismic hazard and risk
analysis performed for decision-making purposes. These two methods can
complement another to provide additional insights to the seismic hazard or risk
problem. One method will have priority over the other depending on how
quantitative are the decisions to be made, Seismic environment and scope of the
project.
Deterministic against probabilistic approaches have differences, advantages, and
disadvantages that often make the use of one advantageous over the other.
Probabilistic methods can be viewed as inclusive of all deterministic events with a
finite probability of occurrence (McGuire, 2001).
16
2.2 Deterministic seismic hazard analysis (DSHA)
Deterministic seismic hazard analysis involves the quantitative estimation of
ground-shaking hazards at a particular site (Kramer, 1996). In deterministic
approach, earthquake magnitude is the magnitude of the largest earthquake capable
of occurring on each seismic source (the maximum creditable earthquake). Faults
and other tectonic features near the site are identified. A suitable attenuation equation
is used to determine the ground motion at the site (Bhatti et al., 2011).
The shortest distance is selected as the source to site distance parameter for the
seismic source zone. After the earthquake magnitude and distance are selected, the
peak horizontal acceleration (PHA) is estimated (Reiter, 1990). The controlling
earthquake is one that produces the highest PHA and the hazard in the site is
formally defined in terms of ground motions produced at the site by the controlling
earthquake (Reiter, 1990).
DSHA provides a framework for evaluation of worst-case ground motions.
However, it provides no information about the likelihood of occurrence of the
controlling earthquake. The frequency of earthquakes and resulting ground motions
are not clearly considered in DSHA. The uncertainties and scientific judgment in
DSHA may not be explicitly recognized and quantified. Figure 2.1 shows the steps in
this approach.
17
Figure 2.1 Steps in Deterministic Seismic Hazard Analysis.
2.3 Probabilistic seismic hazard analysis (PSHA)
The concept of probabilistic seismic hazard has allowed uncertainties in the size,
location and rate of recurrence of the earthquake events. PSHA provides a
framework which uncertainties can be identified, quantified and combined in a
rational manner to provide a more complete picture of the seismic hazard (Kramer,
1996).
In probabilistic approach, site ground motions are estimated for selected values
of the probability of exceedance in a specified return period. PSHA can be
implemented by a four step procedure developed by Reiter, 1990 (Figure2.2):
18
Figure 2.2 Steps in Probabilistic Seismic Hazard Analysis.
1. The first step of PSHA consists of the identification and parameterization of
the seismic sources (known also as source zones, earthquake sources or seismic
zones) that may affect the site of interest. These may be represented as area, fault, or
point sources. Area sources are often used when one cannot identify a specific fault.
In classic PSHA, a uniform distribution of seismicity is assigned to each earthquake
source, implying that earthquakes are equally likely to occur at any point within the
source zone. Seismic source models can be interpreted as a list of potential scenarios,
each with an associated magnitude, location and seismic activity rate (Field, 2005).
2. The next step consists of the specification of temporal and magnitude distributions
of seismicity for each source. The classic, Cornell-McGuire approach, assumes
that earthquake occurrence in time follows the Poisson process. The most often
used model of earthquake magnitude recurrence is the frequency-magnitude
Gutenberg-Richter relationship (Gutenberg and Richter, 1942) .
19
(2.1)
Where is the number of earthquakes with a magnitude of and and (b-
value of Gutenberg and Richter) are constant parameters. It is assumed that
earthquake magnitude belongs to the domain between and , where
is the level of completeness of earthquake catalogue and is the upper limit of
earthquake magnitude for a given seismic source. The parameter is the measure of
the level of seismicity, while describes the ratio between the number of small and
large events.
The seismicity of each seismic source is described by four parameters: the
(annual) rate of seismicity , the lower and upper limits of earthquake magnitude
and and the – of the Gutenberg-Richter relationship.
3. Calculation of ground motion prediction equations and their uncertainty.
Ground motion prediction equations are used to predict ground motion at the site.
The parameters of interest include peak ground acceleration, peak ground velocity,
peak ground displacement, spectral acceleration, intensity, strong ground motion
duration, etc. Most ground motion prediction equations available today are empirical
and depend on the earthquake magnitude, source-to-site distance, type of faulting and
local site conditions (Campbell, 2003; Douglas, 2003; 2004). The choice of an
appropriate ground motion prediction equation is crucial since it is a major
contributor to uncertainty in the estimated PSHA.
4. Integration of uncertainties in earthquake location, earthquake magnitude and
ground motion prediction equation into probability that the ground motion parameter
of interest will be exceeded at the specified site during the specified time interval.
The ultimate result of a PSHA is a seismic hazard curve (McGuire, 2004).
20
The discussion by seismologists about the pros and cons of deterministic and
probabilistic seismic hazard analysis has a long history. Using these approaches
depends on the design level. There are four design levels for structures:
i. Maximum Credible Design level(MCDL)
ii. Maximum Design Level(MDL)
iii. Design Basis Level(DBL)
iv. Construction Level(CL)
MCDL is used for structures with return period of 10000 years(useful life of
structure) so infrastructures such as nuclear power plants or dams in most countries is
still largely based on deterministic seismic hazard analysis.
MDL is considered for return period between 1000 to 5000 years. DBL and CL are
used for 475 and 50 year return period respectively (ICSRDB, 2005).
Structures such as normal buildings, hospitals and schools are based on probabilistic
seismic hazard assessment (Klugel, 2008).
PSHA accounts for some points that DSHA does not consider them. Activity rates
(Number of earthquakes per year) vary from fault to fault in PSHA. In PSHA hazard
increases from multiple faults but in DSHA the hazard for multiple faults is same as
single fault (Figure 2.3).
21
Figure 2.3 Comparison Multiple faults in PSHA and DSHA.
2.4 Previous work
Number of studies (Orozova and Suhadolc, 1999; Romeo and Prestininzi, 2000;
Krinitzsky, 2002) exist in the literature which have been trying to integrate both
probabilistic approach and deterministic approach in a sophisticated engineered
framework.
The majority of the publications in the subject of seismic hazard analysis
concentrate on the application of the probabilistic approaches at different parts of the
world. New challenges in the methodologies used in its development since its
formation (Cornell, 1968; Veneziano et al., 1984; Kebede and van Eck, 1996;
Theodulidis et al., 1998; Kijko and Graham, 1998; Eck and Stoyanov, 1996;
Lindholm and Bungum, 2000; Stirling et al., 2002; Tsapanos, 2003).
Cornell (1968) formulated the theoretical base of ‘deductive’ method developed
for seismic hazard analysis and it was called ‘deductive’ because by applying this
procedure, the causative sources and ground motions for future earthquakes are
deducted. This approach has permitted the incorporation of geological and
geophysical evidence to complete the seismic event catalogues. It is still evident that
deductive procedures of PSHA are dominant and remain the most commonly used
method worldwide.
22
On the other side, the second category of PSHA has been composed of historic
methods (Veneziano et al., 1984). They require input data, such as information about
past seismicity and do not require specification of seismogenic zones.
Kebede and van Eck (1997) performed a probabilistic seismic hazard
assessment for the Africa based on seismotectonic regionalization. The results have
been presented as the regional hazard maps for 0.01 annual probability for intensity
and peak ground acceleration and made the hazard curves for six economically
significant sites. They have also analyzed the model uncertainties with respect to
seismicity in a novel approach by means of a sensitivity analysis quantifying them in
the probabilistic seismic hazard analysis.
The purpose of the study by Theodulidis et al. (1998) has been to suggest a
probabilistic seismic hazard analysis based on the local attenuation relations for peak
ground acceleration and peak ground velocity. This study propose two factors, first
the observed spectral acceleration amplification values and second the expected peak
ground acceleration for mean return period of 500 years.
Kijko and Graham (1998) have described a new methodology for probabilistic
seismic hazard analysis (PSHA) which combines the best features of the deductive
and historical procedures and they called this new approach as ‘parametric-historic’
procedure. Part I of their study presents some of the statistical techniques used for the
assessment and evaluation of the maximum regional magnitude. In Part II the
approach of a probabilistic seismic hazard assessment, which permits the utilization
of incomplete earthquake, catalogues and which takes into account uncertainty in the
determination of the earthquake magnitude is described. Their technique has
provided specifically the estimation of seismic hazard at individual sites, without the
23
psubjective judgment involved in the definition of seismic source zones, in which
specific active faults have not been mapped and identified .
Vaneck and Stoyanov (1996) performed a probabilistic seismic hazard analysis
(PSHA) for southern Bulgaria which represents a typical case of seismic hazard for a
tectonically complex region with large uncertainties in model parameters. They
showed that large uncertainties in seismic characteristics have relatively little effect
on the PSHA output, especially when compared with the uncertainties associated
with the attenuation function. Finally, they claimed that some future improvements
could be handled first by the development of more accurate regional attenuation
models, second by the addition of some constraints on the seismic zones and last by a
better constrain of magnitude-frequency distributions.
Lindholm and Bungum (2000) presented some examples from Norway within a
seismological frame by the aid of a probabilistic seismic hazard. They highlighted
the subject of how a combined seismicity analysis using both modern network data
and historical data can be utilized in order to provide realistic insights into location
precision and to establish magnitude homogeneity. In fact their aim has been to
improve the reliability of the seismic source models (activity parameters) and to
rehabilitate the spatial differentiation of the seismogenic zones. By the objective of
this study they demonstrated how a seismic hazard analysis critically depends on
proper analysis of the underlying seismological information such as the seismicity
catalogue, the attenuation relationships and the magnitude conversions .
On the other hand, Stirling et al. (2002) have presented a new probabilistic
seismic approach for probabilistic seismic hazard analysis (PSHA) to be applied in
New Zealand. This new challenge added as an important feature in the analysis has
24
been the application of a new methodology which combines the modern method
based on the definition of continuous distributions of seismicity parameters with the
traditional method based on the definition of large area sources and the associated
seismicity parameters for the treatment of the historical seismicity data. Their PSHA
has combined the modeled seismicity data with geological data representing the
location and the earthquake recurrence behavior of different active faults and then
incorporated new attenuation relationships specifically developed for New Zealand
to these elements. They stated that the resulting maps have been currently used for
the revision of the building code of the country.
Tsapanos (2003) has also developed a site-specific seismic hazard scenario to be
applied to the sites located in the main cities of Crete Island in Greece in order to
compute the probabilities of exceedance of specific peak ground acceleration (PGA)
values and to predict the maximum possible PGA at each site. According to
Tsapanos (2003). The methodology allows the use of historical or instrumental data,
or a combination of both. The instrumental part of the data can be divided into
subcatalogues with each having an individual minimum threshold magnitude for
completeness and were published maximum possible magnitudes for each site .
Wiemer et al. (2009) have presented the results of a new generation of
probabilistic seismic hazard assessment for Switzerland. This study have replaced the
previous intensity-based generation of national hazard maps and was based on a
revised moment-magnitude earthquake catalogue for Switzerland. Seismic
parameters ( – , – and ) were estimated for earthquake
catalogues of one-million-year duration .they expected ground motions in units of the
5% damped acceleration response spectrum at frequencies of 0.5–10 Hz for all of