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Brief Report for Hunting Creek-Berryessa fault system, Wilson section (Class A) No. 35a

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Compiled in cooperation with the California Geological Survey

citation for this record: Bryant, W.A., compiler, 2000, Fault number 35a, Hunting Creek-Berryessa fault system, Wilson section, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, http://earthquakes.usgs.gov/hazards/qfaults, accessed 10/01/2014 10:22 PM.

Synopsis General: The Hunting Creek-Berryessa is an active (Holocene) dextral strike-slip fault system associated with the larger San Andreas fault system. The Hunting Creek-Berryessa fault system extends from the vicinity of Wilson Valley south-southeast to the Cedar Roughs area west of Lake Berryessa. In this compilation, the fault zone is divided from north to south into the Wilson [35a], Hunting Creek [35b], and Lake Berryessa [35a] sections. The Wilson section probably transfers dextral slip to the Bartlett Springs fault system [29]. The Hunting Creek-Berryessa fault system is expressed as a zone of discontinuous fault traces as much as 3.5 km wide. The Hunting Creek-Berryessa fault system locally is delineated by geomorphic evidence of Holocene dextral strike-slip displacement, predominantly along the Hunting Creek fault, which comprises the Hunting Creek section (Bryant, 1982 #5307; 1983 #5308). An investigation by Steffen, Robertson, and Kirsten, and Woodward-Clyde Consultants (1983 #5310) demonstrated latest Pleistocene and probable Holocene displacement along traces of the Hunting Creek fault. Slip rate and recurrence interval data have not been developed for the Hunting Creek-Berryessa fault system. The investigation by Steffen and others (1983 #5310) inferred a late Pleistocene dextral slip rate of 0.09 mm/yr to 0.4 mm/yr, based on apparent vertical separation of a late Pleistocene to Holocene colluvium. Bryant (1983 #5308) argued that the geomorphic expression of the Hunting Creek fault indicated a dextral slip rate of at least 1 mm/yr.

Sections: This fault has 3 sections. The Hunting Creek-Berryessa fault system is divided into three sections in this compilation. From north to south, the sections are Wilson [35a], Hunting Creek [35b], and Lake Berryessa [35b]. The section boundaries are based in general on a change in geomorphic expression of the faults. The medial Hunting Creek section is delineated by geomorphic evidence of Holocene dextral slip. Both the Wilson and Lake Berryessa sections lack ephemeral geomorphic features indicative of Holocene offset, but are delineated by geomorphic evidence of late Quaternary displacement and they locally offset late Quaternary deposits. Steffen and others (1983 #5310) divided the Hunting Creek fault into 3 segments: from north to south they are the Rieff Road segment, the Dunnigan Hill segment, and the Mysterious Valley segment. There is insufficient data to confirm whether these are seismogenic segments.
County(s) and State(s) YOLO COUNTY, CALIFORNIA
LAKE COUNTY, CALIFORNIA
Physiographic province(s) PACIFIC BORDER
Length (km) This section is 20 km of a total fault length of 56 km.
Average strike N41°W (for section) versus N35°W (for whole fault)
Sense of movement Dextral
Dip Direction W
Historic earthquake
Most recent prehistoric deformation Late Quaternary (<130 ka)
Slip-rate category Between 1.0 and 5.0 mm/yr
Date and Compiler(s) 2000
William A. Bryant, California Geological Survey