Hybrid Broadband Ground-Motion Simulation Using Scenario Earthquakes for the Istanbul Area In ...

109 Pages·2016·19.28 MB·English

Hybrid Broadband Ground-Motion Simulation Using
Scenario Earthquakes for the Istanbul Area

Thesis by
Owais Ahmad Reshi

In Partial Fulfillment of the Requirements for the
Degree of Master of Science

King Abdullah University of Science and Technology,
Thuwal, Kingdom of Saudi Arabia

© April 2016
Owais Ahmad Reshi
All rights reserved
2

The thesis of Owais Ahmad Reshi is approved by the examination
committee.

Committee Chairperson Prof. Dr. P. Martin Mai
Committee Member Prof. Dr. Burt Jones
Committee Member Assoc. Prof. Dr. Sigurjon Jonsson
3

ABSTRACT

HYBRID BROADBAND GROUND-MOTION SIMULATIONS USING
SCENARIO EARTHQUAKES FOR THE ISTANBUL AREA

Owais A. Reshi

Seismic design, analysis and retrofitting of structures demand an intensive assessment of
potential ground motions in seismically active regions. Peak ground motions and
frequency content of seismic excitations effectively influence the behavior of structures.
In regions of sparse ground motion records, ground-motion simulations provide the
synthetic seismic records, which not only provide insight into the mechanisms of
earthquakes but also help in improving some aspects of earthquake engineering.

Broadband ground-motion simulation methods typically utilize physics-based modeling
of source and path effects at low frequencies coupled with high frequency semi-stochastic
methods. I apply the hybrid simulation method by Mai et al. (2010) to model several
scenario earthquakes in the Marmara Sea, an area of high seismic hazard. Simulated
ground motions were generated at 75 stations using systematically calibrated model
parameters. The region-specific source, path and site model parameters were calibrated
by simulating a 𝑀 4.1 Marmara Sea earthquake that occurred on November 16, 2015 on
!
the fault segment in the vicinity of Istanbul. The calibrated parameters were then used to
simulate the scenario earthquakes with magnitudes 𝑀 6.0, 𝑀 6.25, 𝑀 6.5 and 𝑀 6.75
! ! ! !
over the Marmara Sea fault. Effects of fault geometry, hypocenter location, slip
distribution and rupture propagation were thoroughly studied to understand variability in
4

ground motions. A rigorous analysis of waveforms reveal that these parameters are
critical for determining the behavior of ground motions especially in the near-field.
Comparison of simulated ground motion intensities with ground-motion prediction
equations indicates the need of development of the region-specific ground-motion
prediction equation for Istanbul area. Peak ground motion maps are presented to illustrate
the shaking in the Istanbul area due to the scenario earthquakes. The southern part of
Istanbul including Princes Islands show high amplitudes of shaking. The study serves as a
step towards dynamic risk quantification for the Istanbul area that integrates physics-
based ground-motion simulations into an innovative dynamic exposure model to quantify
risk.
5

ACKNOWLEDGEMENTS

I extend my profound gratitude to my supervisor Professor Dr. P. Martin Mai, whose
encouragement, knowledge and support from the beginning to the final level enabled me
to develop an understanding of the subject. This thesis would not have been possible
without his consistent guidance, foresight and optimism. I am very fortunate to have an
advisor like him.

I am grateful to Dr. Kiran K. Thingbaijam for his expert ideas and suggestions. I would
like to thank Dr. Walter Imperatori for helping in removing the bugs in the broadband
ground-motion simulation program. The earthquake team at German Research Centre For
Geosciences (GFZ) Potsdam, especially Professor Fabrice Cotton and Yen-Shin Chen are
kindly acknowledged for the enlightening discussions and suggestions. I am also heartily
thankful to Dr. Martin Galis and Jagdish Vyas for their careful revisions and positive
feedback

I would like to acknowledge the Cat Perils team at Swiss Reinsurance Company (Zurich),
especially Dr. Balz Grollimund and Oliver Kubler for providing me with the opportunity
to work as an intern within the organization. Their guidance and advices are highly
appreciated. It was altogether a great experience.

I owe my sincere gratitude to the Earth Science and Engineering department faculty and
staff for making my time at King Abdullah University of Science and Technology a
6

wonderful experience. I am indebted to my colleagues and friends. Their presence
colored my life.

Finally, my heartfelt gratitude goes to my beloved mother Rafiqa Fayaz, father Fayaz
Reshi, brother Irfan Reshi, sisters Aabida Fayaz and Rahila Majeed for their endless
support, encouragement and love and to my future wife, Suheena Khanday, for her
tremendous inspiration, patience and support.
7

DATA AND RESOURCES

We used COMPSYN software package provided by Paul Spudich to generate low-
frequency waveforms. The kinematic rupture models were constructed using rupture
model generator package developed by Dr. P. Martin Mai downloaded from
http://equake-rc.info. BBsimulations toolbox, F90 code to compute broadband
waveforms, was also available at http://equake-rc.info (last accessed November 2, 2015).
The earthquake catalogue data and the recordings of 𝑀 4.1 Marmara Sea earthquake
!
(occurred on November 16, 2015) were collected from the website of Republic of Turkey
Prime Ministry Disaster and Emergency Management Authority (http://deprem.gov.tr last
accessed November 22, 2015). Shear wave velocity (Vs30) data was downloaded from
the website of United States Geological Survey
(http://earthquake.usgs.gov/hazards/apps/vs30/predefined.php last accessed February 26,
2016). The Matlab codes to compute peak-ground intensities using GMPEs were
provided by Baker Research Group at Stanford University
(https://web.stanford.edu/~bakerjw/GMPEs.html, last accessed March 04, 2016). The
shape file defining the boundaries of Istanbul was obtained from
http://www.statsilk.com/maps/download-free-shapefile-maps (last accessed October 21,
2015). Some facts about the Istanbul area were obtained from
(http://www.turkstat.gov.tr last accessed March 21, 2016)
8

TABLE OF CONTENTS

EXAMINATION COMMITTEE APPROVALS FORM .......................................... 2
ABSTRACT ............................................................................................................... 3
ACKNOWLEDGEMENTS ...................................................................................... 5
DATA AND RESOURCES ....................................................................................... 7
TABLE OF CONTENTS ........................................................................................... 8
LIST OF ABBREVIATIONS .................................................................................... 10
LIST OF SYMBOLS ................................................................................................ 12
LIST OF FIGURES ................................................................................................... 13
LIST OF TABLES ..................................................................................................... 17
CHAPTERS
1. INTRODUCTION .............................................................................................. 18
2. TECTONIC SETTINGS AND SEISMICITY .................................................... 24
3. SIMULATION METHOD .................................................................................. 32
3.1. Low-Frequency Simulations ....................................................................... 32
3.1.1. Source Characteristics .......................................................................... 34
3.2. HF Simulation and Reconciliation with LF Seismograms ......................... 35
4. CALIBRATION OF GROUND MOTION PARAMETERS ............................. 40
4.1. Calibration of LF Part ................................................................................. 43
4.2. Calibration of HF Part ................................................................................. 45
4.3. Effect of Hypocentral Depth on the Ground Motion Amplitudes .............. 49
5. INFLUENCE OF FAULT GEOMETRY ON GROUND MOTIONS ............... 51
6. SETTING UP OF SCENARIO RUPTURES ..................................................... 59
7. RESULTS AND DISCUSSIONS ....................................................................... 66
7.1. Influence of Hypocenter Location and Slip ................................................ 67
7.2. Comparison with Ground-Motion Prediction Equations ............................ 70
7.3. A Concise Variability Test .......................................................................... 76
7.4. Peak Ground Motion Maps ......................................................................... 79
8. CONCLUSIONS ............................................................................................... 84
REFERENCES .......................................................................................................... 89
APPENDIX ................................................................................................................ 100
A.1. Some Information About Earthquake Geometry and Definition of Some
Important Earthquake-Related Parameters .................................................... 100
A.2. Some Important Wave Propagation Equations Used in the Simulation
Programs ........................................................................................................ 102
A.2.1. COMPSYN ......................................................................................... 102
A.2.2. Broadband Simulations ....................................................................... 103
A.3. Effect of Slip Distribution on Ground-Motion Amplitudes for 𝑀 4.1
!
9

Earthquake .................................................................................................... 103
A.3. Sample Rupture Models Used in this Study .................................................. 105
A.4. Extended Figures of Waveform Analysis from the Text ............................... 106
A.5. Station Coordinates ........................................................................................ 108
10

LIST OF ABBREVIATIONS

DWFE Discrete Wavenumber Finite Element
ERD Earthquake Research Department
ERS European Remote Sensing
FAS frequency acceleration spectra
FN fault-normal
FP fault-parallel
GMPEs ground-motion prediction equations
GEM Global Earthquake Model
HF high frequency
KOERI Kandilli Observatory and Earthquake Research Institute
LF low frequency
Lat. latitude
Lon. longitude
NAF North Anatolian Fault
NAFZ North Anatolian Fault Zone
NGA Next Generation Attenuation
OSM Open Street Map
PGA peak ground acceleration
PGV peak ground velocity
PSA peak spectral acceleration
SDOF single-degree-of-freedom