Zadonina E.O. (1) , Caldeira B. (1,2) , Bezzeghoud M. (1,2), Borges J.F. (1,2)
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Transcript of Zadonina E.O. (1) , Caldeira B. (1,2) , Bezzeghoud M. (1,2), Borges J.F. (1,2)
Zadonina E.O. (1), Caldeira B. (1,2), Bezzeghoud M. (1,2), Borges J.F. (1,2)
(1) Centro de Geofísica de Évora
(2) Departamento de Física, Universidade de Évora
I. Slip distribution, co-seismic deformation and
Coulomb stress change for the 12 May 2008 Wenchuan (China,
Mw7.9) earthquakeII. Influence of model parameters on synthesized high-frequency strong-
motion waveforms
Study of a recent large earthquake
Determine a slip model by inverting teleseismic body waves
Confront the obtained model to various independent datasets
I. Objectives
12 May 2008 – Wenchuan Earthquake Mw 7.9 (China)
Occurred on the boundary between Longmen Shan and Sichuan basin (31.1˚ N, 103.3˚ E) at the 19 km depth
Claimed 69,000 lives
I. The Wenchuan earthquake
Wen
chua
nBei
chu
anAna
xia
n
Zipingpu Dam
I. Longmen Shan fault zone
Google Earth image Wanju et al, 2008
Sichuan basin
Preprocessing of teleseismic body waves and determination of source parameters
Inversion of teleseismic body-waves with Kikuchi and Kanamori's algorithm to obtain slip distribution
Modeling of horizontal displacements and Coulomb stress change
Comparison of obtained results with GPS data and aftershocks distribution
I. Methodology
I. Spatial destribution of seismic stations
I. Results : co-seismic slip distribution
I. Results: rupture propagationTime of
rupture > 90 sRise time ~
30 s
I. Results: horizontal displacement
Observed
Modeled
Projection of upper edge of fault
plane onto the surface
I. Aftershocks distributionData about
aftershocks was taken for the period of 3 month after the main event
3<Mw<73 km<Depth<32 km
I. Results: changes in Coulomb stress produced by the Wenchuan earthquake
Stress increase
Stress release
Δσс = Δτ - μ’Δσn
μ’ = μ(1 - B)
Obtained horizontal surface displacement not in the strict agreement with observed data
Changes in static Coulomb stress are consistent with aftershock distribution down to a depth of 7 km
Perspective – refining of existing source parameters and slip model; joint inversion of strong motion data and InSAR data
I. Conclusions and perspectives
Synthesize high-frequency near-fault waveforms produced by hypothetical earthquake with certain parameters
Numerically estimate the influence of some of the used parameters – source time function, geometry of a fault plain, variations in velocity model, rupture velocity - on the waveforms
Use obtained knowledge in synthesis of waveforms of real event – The Alum Rock earthquake occurred on October 30, 2007 using the existing slip model of the event and Community Velocity Model SCEC CVM-H 6.2
II. Objectives
2D/3D elastic finite-difference wave propagation code E3D based on the elastodynamic formulation of the wave equation on a staggered grid
Misfit Criteria for Quantitative Comparison of Seismograms by Miriam Kristeková et al.
II. Methodology
October 30, 200737,43 N, 121,78 WMw 5.69.2 km depthStrike: 323˚Dip: 87 ˚Rake: -180 ˚
Slip distribution by Margaret Hellweg et al.
II. Alumn Rock earthquake
II. Near-field accelerograms
II. Basic formulas dt
a
btts
ats
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)(CWT ba,
)2/exp()exp()( 20
4/1
ttit
ftREFftft WWE ,,,
),(),(
),(,ftREFft
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)(max ),(,
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),(,
ftREFft
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Thank you for your attention!