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Data Release for the 2016 East Bay Seismic Imaging Investigation of the Hayward Fault Zone

August 3, 2021

In October 2016, we acquired an approximately 15-km-long seismic profile along a linear transect across the East Bay region of the San Francisco Bay area. Our goal was to image previously unknown strands of the Hayward Fault zone and to better delineate the structure and geometry of the main trace of the Hayward Fault. Our profile started near the southern border of San Leandro, California at the San Francisco Bay shoreline, trended ENE through the northern edge of Castro Valley, California, and ended approximately 5 km WSW of San Ramon, California. The data were analyzed using refraction tomography modeling, reflection processing, and guided-wave analysis. The analyzed data are presented in separate reports by Strayer and others (submitted to BSSA). The seismic data were generated at 26 shotpoints: 16 shotpoints located along the profile (inline shotpoints) and 10 shotpoints offset from the profile and located within known or suspected fault traces (guided-wave shotpoints). Most shotpoints used explosive sources to generate the seismic waves, but three of the shotpoints used repeated hits from a 227-kg (500 lb) accelerated weight dropped ~2 feet above a steel plate to generate the seismic signal. Data from each shot were recorded by a total of 459 seismographs, mostly deployed along the profile at intervals ranging from 20 to 100 meters. This data release contains the raw field records from all explosive and weight drop shots. The raw field records are in a proprietary TRD format and consist of continuous seismograph recordings during the time of the data collection. Also included in this data release are multiple SEG-Y files consisting of thirty-second-long traces "cut" from the TRD files and resorted into conventional shot gathers. These data are in standard SEG-Y format, with the data samples in IBM floating point format. Data samples are in units of meters/second, without filtering or other data manipulation.