The Pleasanton Fault is a
seismic
Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes (or generally, quakes) and the generation and propagation of elastic ...
ally active
geological
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth s ...
structure in
Alameda County
Alameda County ( ) is a county located in the U.S. state of California. As of the 2020 census, the population was 1,682,353, making it the 7th-most populous county in the state and 21st most populous nationally. The county seat is Oakland. A ...
and
Contra Costa County, California
Contra Costa County (; ''Contra Costa'', Spanish for 'Opposite Coast') is a county located in the U.S. state of California, in the East Bay of the San Francisco Bay Area. As of the 2020 United States census, the population was 1,165,927. Th ...
, US. The existence of the fault is disputed as geotechnical reports have found no evidence for its existence.
Relation to hydrological features
All the streams draining
Livermore Valley
The Livermore Valley, historically known as the Valle de San José (Valley of San José), is a valley in Alameda County, California, located in the East Bay region. The city of Livermore is located in the valley. The valley became known as "Liver ...
merge above the
Bernal Subbasin and then leave the subbasin and the valley as the
Arroyo de la Laguna
Arroyo de la Laguna is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed March 15, 2011 southward-flowing stream in Alameda County, California, United States which originates at the con ...
. Groundwater occurs throughout the valley floor portion of the Bernal Subbasin under conditions ranging from unconfined to confined. There is no inflow of groundwater across the Pleasanton Fault south of the
City of Pleasanton. This consequence arises because any movement of groundwater in the southern section is essentially parallel to the Pleasanton Fault.
[Earth Metrics Incorporated, ‘'Environmental Site Assessment for the Hopyard Village Shopping Center, Pleasanton, California'‘, May 24, 1989]
See also
*
Mocho Subbasin
The Mocho Subbasin is the largest of the groundwater subbasins in the watershed of the Livermore Valley in Northern California. This subbasin is bounded to the west by the Livermore Fault Zone and to the east by the Tesla Fault. Some groundwate ...
*
Tesla Fault
The Tesla Fault can be found in the northeastern Diablo Range, California. This fault is only semi-active.
Geology
This fault has been demonstrated to have a dextral offset of and is closely associated with the Greenville Fault.
Mocho Subbas ...
References
External links
Bulletin of the Seismological Society of America; December 1971; v. 61; no. 6; p. 1795-1799; 1971 Seismological Society of America, NATIONAL CENTER FOR EARTHQUAKE RESEARCH U. S. GEOLOGICAL SURVEY, MENLO PARK, CALIFORNIA
Seismic faults of California
Geology of Alameda County, California
Geology of Contra Costa County, California
Livermore Valley
Geography of Pleasanton, California
Livermore, California
Geography of the San Francisco Bay Area
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