[First Hit]

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Abstract: Holocene Earthquakes on the Southern Sargent Previous HitFaultNext Hit, San Benito County, California

Erik N. Zinn, Jeffrey M. Nolan, Gerald E. Weber

The Sargent Previous HitfaultNext Hit extends for 45 kilometers across San Benito and Santa Clara Counties, California. At its northern terminus, the Previous HitfaultNext Hit appears to merge with the San Andreas Previous HitfaultNext Hit near Lake Ellsman north of Loma Prieta mountain. The Previous HitfaultNext Hit may connect with the Calaveras Previous HitfaultNext Hit south of Hollister, California at its southern terminus. The Sargent Previous HitfaultNext Hit appears to provide the primary control of the geomorphic development of Lomerias Muertas and the Flint Hills northwest of Hollister. Previous estimates of Previous HitfaultNext Hit movement inferred from geomorphic expression are right-lateral reverse-oblique with the southwest side up.

Two trenches were excavated across the Previous HitfaultNext Hit in Holocene sediments underlying the flood plain of the Pajaro River, north of Lomerias Muertas. The exposed Previous HitfaultNext Hit dips 70 degrees to the northeast, contrary to previous characterizations of the Previous HitfaultNext Hit, and displays down to the northeast, normal separation, although slickensides on the Previous HitfaultNext Hit surface indicate a primarily horizontal slip vector. At least two Holocene rupture events are suggested by offsets of the stratigraphic section. Dating of C14 samples presently in progress is expected to yield a Holocene slip rate for the Previous HitfaultTop. Funding for this project was provided by USGS National Earthquake Hazards Reduction Program award #1434-94-G2466.

AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California