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Towards Structural Imaging Using Scattering Artifacts Detected in Ambient Field Correlations

Lise Retailleau, & Gregory C. Beroza

Published August 15, 2018, SCEC Contribution #8445, 2018 SCEC Annual Meeting Poster #304

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.

The waves that comprise the ambient field are subject to scattering due to the heterogeneous earth which can generate supplementary arrivals on the correlations functions. It is possible to use these effects of scattering that do not correspond to the propagation between the two stations considered, to locate potential external sources of signal.
For this analysis, we use correlation functions computed from continuous signals recorded between 2001 and 2017 by seismic stations in Central California. We identify supplementary arrivals in the correlation functions and use array analysis to map the source of scattering effects linked to strong structural variations.

We are particularly interested in imaging scatters that result in coupling between the P-SV and SH systems because they are a consequence of lateral heterogeneities in Earth structure. For that reason, we particularly focus on components of the correlation tensor, different from the Vertical-Vertical component, and we expect the Radial/Vertical to Transverse components to be particularly helpful.

Retailleau, L., & Beroza, G. C. (2018, 08). Towards Structural Imaging Using Scattering Artifacts Detected in Ambient Field Correlations. Poster Presentation at 2018 SCEC Annual Meeting.

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