Identification_Information: Citation: Citation_Information: Originator: U.S. Geological Survey Originator: Coastal and Marine Geology Team(ed.) Originator: Western Region Publication_Date: Unknown Publication_Time: Unknown Title: Marine Seismic Reflection Profiles Data of San Francisco Bay Area Geospatial_Data_Presentation_Form: remote-sensing image Description: Abstract: Dataset consists of two-dimensional marine seismic reflection profile data from the San Francisco Bay area. These data were acquired in 1993, with the vessel David Johnston. The USGS identifier for these data is J893SF. Purpose: Marine seismic reflection data are used to image and map sedimentary and structural features of the seafloor and subsurface. These data are useful in mapping faults (such as the San Andreas and Hayward Faults) where they pass under the waters of the San Francisco Bay, and in assessing other submarine geologic characteristics and features. Supplemental_Information: 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 water behind 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 hydro- phone. This process is repeated at intervals ranging between 250 milliseconds and 10 seconds depending on the source type. In this way a two-dimensional image of the geologic structure beneath the ship track is constructed. Seismic data are stored in SEG-Y format, which is a standard digital format that can be read and manipulated by most seismic-processing software packages. The SEG-Y file format includes a 3200-byte descriptive header that should contain detailed information regarding the data acquisition and processing parameters. The navigation data are stored in flat ASCII files as latitude and longitude values that can be used to plot track maps of the seismic profiles at any scale or map projection desired. The data and format of the navigation files are described in the file prologue. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 19991005 Currentness_Reference: Publication Date Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -122.583333 East_Bounding_Coordinate: -122.83333 North_Bounding_Coordinate: +37.5000 South_Bounding_Coordinate: +38.08333 Keywords: Theme: Theme_Keyword_Thesaurus: General Theme_Keyword: marine seismic reflection profile Theme_Keyword: SEG-Y data Theme_Keyword_Thesaurus: Field_id Theme_Keyword: J893SF Theme_Keyword: David Johnston Place: Place_Keyword_Thesaurus: Geographic Place_Keyword: San Francisco Bay Place_Keyword: San Pablo Bay Place_Keyword: Golden Gate Place_Keyword: Northern California Place_Keyword: San Andreas Fault Place_Keyword: Hayward Fault Access_Constraints: None Use_Constraints: U.S. Geological Survey requests to be acknowledged as the data collector in any publication or other use of these data. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Jonathan R. Childs Contact_Organization: U.S. Geological Survey Contact_Position: geophysicist Contact_Address: Address_Type: mailing and physical address Address: U.S. Geological Survey Mail Stop 999 345 Middlefield Rd. City: Menlo Park State_or_Province: CA Postal_Code: 94025 Contact_Voice_Telephone: 650-329-5195 Contact_Electronic_Mail_Address: jchilds@usgs.gov Metadata_Reference_Information: Metadata_Date: 19991005 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Clint Steele Contact_Address: Address_Type: mailing and physical address Address: U.S. Geological Survey Mail Stop 999 345 Middlefield Rd. City: Menlo Park State_or_Province: CA Postal_Code: 94025 Contact_Voice_Telephone: 650-329-5055 Contact_Electronic_Mail_Address: csteele@usgs.gov Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: June 8, 1994