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Rapid Centroid Moment Tensor (CMT) Inversion in 3D Earth Structure Model for
Earthquakes in Southern California
1En-Jui Lee, 1Po Chen, 2Thomas H. Jordan, 2Philip Maechling, 3Yifeng Cui, 2Scott Callaghan
1University of Wyoming, 2University of Southern California, 3San Diego Supercomputer Center
Overview
• Introduction• Methodology• Results• Reduce source errors for tomo. • (Near) Real-time application • Summary
Introduction• Earthquake-prone
area• 244 broadband
stations• Seismic hazard
analysis• Realistic
interpretation of geological structures
Introduction• 3D updated
velocity model: CVM4SI2
• Improved model better source estimations
Our current tomography results
4:45 pmBallroom D
Source inversion
Automatic window picking
Broadband Data Waveforms
Selected Windows
NCC between data & synthetic
Measurements (NCC, dt, lnA)
Optimal CMT Solution
Bayesian inference
Automatic window picking• Less heterogeneity effects : P, Pnl, S & surface
waves• Continuous wavelet transform (CWT)• Topological watershed (TW)
Source inversion
Automatic window picking
Broadband Data Waveforms
Selected Windows
NCC between data & synthetic
Measurements (NCC, dt, lnA)
Optimal CMT Solution
Bayesian inference
Synthetic seismograms• Any M is linear combination of elementary
seismograms M1 ~ M6• Different subgroups can represent the specific
solutions1
Kikuchi & Kanamori, 1991
Measurements• NCC between data windows & synthetic
seismogram NCC, dt, lnA
Source inversion
Automatic window picking
Broadband Data Waveforms
Selected Windows
NCC between data & synthetic
Measurements (NCC, dt, lnA)
Optimal CMT Solution
Bayesian inference
Bayesian inference• Apply the Bayesian inference to different type
of measurements (Ncc, dt and lnA)• Assuming the measurements are independent• Select the CMT with highest probability
Example of Yorba Linda event• 2002/09/03 Mw 4.3
Results• Compare synthetic waveforms between 1D
multi-layer and 3D models
• An example of small earthquake (ML=3.13)
• Comparison of relocated depths
• Comparison of magnitude estimations
Synthetic waveform comparisons
An example of ML=3.13 earthquake
Comparison of relocated depths
An example of depth comparison
Comparison of magnitude estimations
Reduce source errors for tomography
(Near) Real-time application• Using 10 sec of 2008 Chino Hills earthquake • find an optimal solution in 20 secs (4 cores)
Summary• Rapid and accurate CMT solution
– Store RGTs rapid– 3D velocity structure accurate waveforms
• By applying Bayesian inference provide uncertainty estimates for the source parameters
• Potential application for (near) real-time source inversion (near) real-time ground motion forecast
• Probabilistic Seismic Hazard Analysis (PSHA) - CyberShake
Thank You!
Go tohttp://www-rcf.usc.edu/~pochen/
for PDF preprints and reprints
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