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Chirp seismic-reflection data: San Pablo Bay, California

June 17, 2016

This data release includes chirp seismic-reflection data collected in 2014 aboard the USGS R/V Snavely in San Pablo Bay, part of northern San Francisco Bay. These data were acquired to image the shallow geologic structure, particularly that related to the Hayward and Rodgers Creek Faults. Approximately 200 km of marine seismic-reflection data were collected along primarily northeast and northwest-trending profiles spaced 1-km apart using an Edgetech 512 chirp sub-bottom profiler that was towed alongside the vessel on a sled at the sea surface. Data were acquired using a 2-12 kHz sweep with a 20 ms length fired 6 times per second. Initial processing included subsampling at twice the sample interval to make swell correction more effective. Additional processing included swell correction, predictive deconvolution, and trace mixing. Due to attenuation of the chirp signal by bay muds and persistent natural gas layers in San Pablo Bay sediments, we were only able to image the upper 2 to 5 meters of the sub-seafloor. Both raw data in SEG-Y format and processed data ("Processed SEG-Y") are provided here.