High-Resolution Marine Seismic Reflection Data From the San Francisco Bay Area, USGS/OFR 00-494

These data were acquired between 1993 and 1997 with the Research Vessels David Johnston and Robert Gray. The data are available in a variety of formats, including binary, postscript and GIF image. Binary data are in Society of Exploration Geologists (SEG) SEG-Y format and may be downloaded for further processing or display.

Reference maps and GIF images othe profiles may be viewed with your Web browser. Seismic reflection profiles are acquired by means of an acoustic source (usually generated electromagnetically or with compressed air), and a hydrophone or hydrophone array. Both elements are typically towed in the waterbehind a survey vessel.

The sound source emits a short acoustic pulse, which propogates through the water and sediment columns. The acoustic energy is reflected at density boundaries (such as the seafloor or sediment layers beneath the seafloor), and detected at the hydrophone. As the vessel moves, this process is repeated at intervals ranging between 0.5 and 20 meters depending on the source type.

In this way a two-dimensional image of the geologic structure beneath the ship track is constructed.