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Tomography of Central California Using Ambient Field Correlations

Lise Retailleau, Aurelien Mordret, & Gregory C. Beroza

Published August 12, 2019, SCEC Contribution #9463, 2019 SCEC Annual Meeting Poster #311

Correlations of the ambient seismic field have been used successfully for tomographic imaging of the Earth on a wide range of scales. This is based on the theoretical and experimental observations that correlation functions computed between the signals recorded by two stations contain an approximation of the impulse response (Green’s function) between these stations.

Numerous seismic sensors have been installed during the last decades in California and have recorded continuously ambient seismic field. These signals give the opportunity to image the Central California upper crust structure using ambient noise correlations. For the time period between 2001 and 2015, we are able to compute the correlation tensor between hundred pairs of stations. We measure the group and phase velocity for Rayleigh and Love waves, on the ZZ and TT components, respectively for the period range 5 s to 20 s. The velocities at each period are regionalized using a regularized straight-ray scheme and the local dispersion curves for Love and Rayleigh waves are jointly inverted to obtain shear-wave velocity vs. depth profiles. The final 3D velocity model clearly highlights the Central Valley sedimentary basin as well as higher velocity in Coastal Ranges and the Sierra Nevada batholith.

Retailleau, L., Mordret, A., & Beroza, G. C. (2019, 08). Tomography of Central California Using Ambient Field Correlations. Poster Presentation at 2019 SCEC Annual Meeting.

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SCEC Community Models (CXM)