From November 2011 to August 2015, the U.S. Geological Survey (USGS) collected more than 1,000 line-kilometers (length of lines surveyed in kilometers) of marine magnetic data on San Pablo Bay, 98 onshore gravity stations, and over 27 line-kilometers of ground magnetic data in northern California. Combined magnetic and gravity investigations were undertaken to study subsurface geologic structures as an aid in understanding the geologic framework and earthquake hazard potential in the San Francisco Bay Area. Furthermore, marine magnetic data illuminate local subsurface geologic features in the shallow crust beneath San Pablo Bay where geologic exposure is absent.
Magnetic and gravity methods, which reflect contrasting physical properties of the subsurface, are ideal for studying San Pablo Bay. Exposed rock units surrounding San Pablo Bay consist mainly of Jurassic Coast Range ophiolite, Great Valley sequence, Franciscan Complex rocks, Miocene sedimentary rocks, and unconsolidated alluvium (Graymer and others, 2006). The contrasting magnetic and density properties of these rocks enable us to map their subsurface extent.
Ponce, D.A., Denton, K.M., and Watt, J.T., 2016, Marine magnetic survey and onshore gravity and magnetic survey, San Pablo Bay, northern California: U.S. Geological Survey Open-File Report 2016–1150, 14 p., http://dx.doi.org/10.3133/ofr20161150.
ISSN: 2331-1258 (online)
Table of Contents
- Magnetic Data
- Gravity Data
- References Cited
|Publication Subtype||USGS Numbered Series|
|Title||Marine magnetic survey and onshore gravity and magnetic survey, San Pablo Bay, northern California|
|Series title||Open-File Report|
|Publisher||U.S. Geological Survey|
|Publisher location||Reston, VA|
|Contributing office(s)||Geology, Minerals, Energy, and Geophysics Science Center|
|Description||Report: iv, 14 p.; 3 Tables; Metadata|
|Other Geospatial||San Pablo Bay|
|Online Only (Y/N)||Y|
|Additional Online Files (Y/N)||Y|
|Google Analytic Metrics||Metrics page|