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U.S. Geological Survey
Open-File Report 2006-1084
Version 1.0

Subsurface Structure of the East Bay Plain Ground-Water Basin: San Francisco Bay to the Hayward Fault, Alameda County, California

By R.D. Catchings, J.W. Borchers, M.R. Goldman, G. Gandhok, D.A. Ponce, and C.E. Steedman


photo of marsh grass, bay muds, the Bay, and the hills beyond.  A row of small maker flags extends out into the water

The area of California between the San Francisco Bay, San Pablo Bay, Santa Clara Valley, and the Diablo Ranges (East Bay Hills), commonly referred to as the "East Bay", contains the East Bay Plain and Niles Cone ground-water basins. The area has a population of 1.46 million (2003 US Census), largely distributed among several cities, including Alameda, Berkeley, Fremont, Hayward, Newark, Oakland, San Leandro, San Lorenzo, and Union City. Major known tectonic structures in the East Bay area include the Hayward Fault and the Diablo Range to the east and a relatively deep sedimentary basin known as the San Leandro Basin beneath the eastern part of the bay. Known active faults, such as the Hayward, Calaveras, and San Andreas pose significant earthquake hazards to the region, and these and related faults also affect ground-water flow in the San Francisco Bay area. Because most of the valley comprising the San Francisco Bay area is covered by Holocene alluvium or water at the surface, our knowledge of the existence and locations of such faults, their potential hazards, and their effects on ground-water flow within the alluvial basins is incomplete.

To better understand the subsurface stratigraphy and structures and their effects on ground-water and earthquake hazards, the U.S. Geological Survey (USGS), in cooperation with the East Bay Municipal Utility District (EBMUD), acquired a series of high-resolution seismic reflection and refraction profiles across the East Bay Plain near San Leandro in June 2002. In this report, we present results of the seismic imaging investigations, with emphasis on ground water.

Download this publication as a PDF file (of2006-1084.pdf; 61 pages - 16 MB, with links to seven oversized figures in a 37-MB figures folder). Note: the oversized figures are many feet wide; they can be viewed nicely by zooming in and panning to the side. To print them, you will need a plotter.

For questions about the content of this report, contact Rufus Catchings

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Maintained by: Michael Diggles
Created: June 16, 2006
Last modified: October 13, 2009 (mfd)