Multiscale seismic imaging of the San-Andreas-Fault system

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The main objective of project SAFOD (San-Andreas-Fault-Observatory-at-Depth) is to answer fundamental questions about the physical and chemical processes controlling faulting and earthquake generation within a major plate-bounding fault. In that respect significant progress has been achieved recently by acquiring and analyzing various geoscientific data sets. We propose to contribute to this understanding by constructing detailed crustal transects across this plate boundary zone from seismic imaging on different scales. On one hand we want to reprocess existing industry seismic reflection data and USGS seismic refraction data ("SJ6" transect) using innovative seismic imaging techniques (Fresnel-Volume-Migration) in order to map and to analyze its large-scale structural inventory and tectonic environment. We expect that such a reprocessing will resolve in particular the large-scale depth structure and the deep roots of the San-Andreas-Fault system, which has not yet been achieved using recent seismic data sets. On the other hand we want to process microseismic data recorded within the SAFOD borehole, which have illuminated nearby branches of the fault system, using reflection seismic techniques in order to reveal the fine-scale fault structure in the close vicinity of the borehole. These imaging results can be directly used as a calibration tool for seismological investigations as well as borehole studies during the ongoing drilling phase at SAFOD. This multiscale approach will deliver comprehensive seismic images which can be used as a basis for a profound characterization of the subsurface environment and can decisively contribute to the understanding of the seismogenic processes at this major plate bounding fault system.