The Calaveras fault is a right-lateral strike-slip fault that is part of the San Andreas system (the
Pacific-North America plate boundary). Its creep rateof 10-12 mm/yr is just about as large as
its slip rateof 12 mm/yr, meaning that all (or almost all) of the fault motion occurs as creep,
reducing the chance and size of major earthquakes.

The Calaveras fault branches from the San Andreas fault just south of Hollister; to the north it
runs through Anderson reservoir, Calaveras reservoir, and through the San Ramon Valley (I-680)
before dying out near Mt. Diablo. From Morgan Hill north, the Calaveras does not spend all of
its motion on creep; instead, some of it builds up to produce M6-6.5 earthquakes like the 1984
Morgan Hill earthquake.

Field trip directions (from San Jose):Take U.S. 101 south to Hollister exit, State Route 25.
Proceed south on Rt. 25 into Hollister. Turn right (west) on Third St., continue after it changes to
Virginia St., park and meet at corner of Virginia and Locust.

Three strands of the Calaveras fault are shown on the accompanying map. The two lesser traces
are shown by dashed lines. The main trace is shown as a solid line west of Park Hill. Your job:
Show the southward continuation of the main trace, starting at Locust St./Ave. and continuing
across the page. Use a solid line.

Things to look for:

bent curbs & sidewalks offset curbs & sidewalks "thrusting" of sidewalk slabs warped buildings (garages, houses, etc.) offset walls different effects on concrete and wood

NOTE: Please use great caution crossing 4th St., a major thoroughfare with no stop sign.