TY  - JOUR
AU  - Tape Carl, Liu Qinya
PY  - 2010//
TI  - Seismic tomography of the southern California crust based on spectral-element and adjoint methods
JO  - Geophysical Journal International
SP  - 433
EP  - 462
VL  - 180
IS  - 1
PB  - Blackwell Publishing Ltd
KW  - Inverse theory
KW  - Body waves
KW  - Surface waves and free oscillations
KW  - Seismic tomography
KW  - Computational seismology
KW  - Crustal structure
KW  -
N2  - SUMMARY We iteratively improve a 3-D tomographic model of the southern California crust using numerical simulations of seismic wave propagation based on a spectral-element method (SEM) in combination with an adjoint method. The initial 3-D model is provided by the Southern California Earthquake Center. The data set comprises three-component seismic waveforms (i.e. both body and surface waves), filtered over the period range 230 s, from 143 local earthquakes recorded by a network of 203 stations. Time windows for measurements are automatically selected by the FLEXWIN algorithm. The misfit function in the tomographic inversion is based on frequency-dependent multitaper traveltime differences. The gradient of the misfit function and related finite-frequency sensitivity kernels for each earthquake are computed using an adjoint technique. The kernels are combined using a source subspace projection method to compute a model update at each iteration of a gradient-based minimization algorithm. The inversion involved 16 iterations, which required 6800 wavefield simulations. The new crustal model, m16, is described in terms of independent shear (VS) and bulk-sound (VB) wave speed variations. It exhibits strong heterogeneity, including local changes of ±30 per cent with respect to the initial 3-D model. The model reveals several features that relate to geological observations, such as sedimentary basins, exhumed batholiths, and contrasting lithologies across faults. The quality of the new model is validated by quantifying waveform misfits of full-length seismograms from 91 earthquakes that were not used in the tomographic inversion. The new model provides more accurate synthetic seismograms that will benefit seismic hazard assessment.
SN  - 1365-246X
UR  - http://dx.doi.org/10.1111/j.1365-246X.2009.04429.x
N1  - exported from refbase (http://publi.ipev.fr/polar_references/show.php?record=514), last updated on Fri, 05 Jul 2024 21:30:51 +0200
ID  - TapeCarl2010
ER  -