Seismic Daylight Imaging: A New Passive-Seismic Method to Image Basin and Crustal Structure

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Abstract for proposal EAR0106693 (PH # 21x)Title: "Seismic Daylight Imaging: A new passive-seismic method to image basin and crustal structure" PI's: Klemperer and Claerbout, Stanford Univ.We are developing a new passive-seismic imaging technique that we call "Seismic Daylight Imaging" (SDI), and will test its ability to image basin and crustal structure beneath the San Clara Valley in the San Francisco Bay area, California. We hope SDI can supplement more costly active-source (i.e., typically small dynamite explosions) seismic imaging, and even possibly supplant active-source shooting in cases where extreme building density and cultural noise precludes the traditional active-source methodology. We will produce a seismic image of the crustal structure beneath the Santa Clara Valley, similar to one produced by an active-source seismic survey, but with less resolution. Thus we will add to existing knowledge of central California tectonics by delineating important crustal structures such as midcrustal detachments and sedimentary basin depths. We will also improve microzonation of earthquake hazards in Santa Clara Valley by constraining basin depths and velocity profiles.SDI is a relatively simple, but time consuming process. Using existing data recently acquired in the Santa Clara Valley Seismic Experiment (SCVSE), seismic traces from the entire data set will be cross-correlated, one hour at a time, beginning with the vertical channel, and stacked. The cross-correlations will result in a cube of virtual seismic shot records, which will then be migrated to produce a 3-D seismic image of crustal structure beneath the Santa Clara Valley. Our SDI image will be compared with a linear high-resolution active-source seismic survey that has recently been conducted by the USGS in the same area.