Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, Joe Dellinger. |
(Left) Not far away from the town of Hollister is the Almaden Cienega Winery. The winery is located squarely across the San Andreas fault trace, and has been affected by fault creep. Measurements of the alignments of the culvert and floor slabs show a relative offset rate across the San Andreas fault of 1.5 centimeters per year. Small springs abound along this trace. In this photo taken on April 12, 1986, Mr. Dedear is standing astride an open concrete culvert which lies just to the south of the winery. (Right) Another view of the same culvert at Almaden Cienega winery, showing the offset across the fault as it appeared in May, 1990. Image Credit: Joe Dellinger. Seismic creep is the constant or periodic movement on a fault as contrasted with the sudden rupture associated with an earthquake. It is a usually slow deformation of rock resulting from constant stress being applied over a period of time. Sometimes aseismic slip is observed at the ground surface along a ruptured fault that has produced a substantial earthquake. Examples are from the Hollister and Hayward, California, region. Several of the slides are split images of a location, comparing fault movement over the years. |
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