Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, Joe Dellinger. |
This small, seemingly-insignificant crack indicates the location of the Calaveras fault crossing Locust Street near the intersection with Central Street. The photo looks straight down the fault trace. The fault trace runs along the right middle part of the photo from the near foreground to behind the blue truck. The individual cracks themselves tend to be perpendicular to the curb. They are en echelon cracks. The individual cracks stack together like shingles at the edge of a roof line. The fault cracks at Hollister are remarkably localized. If the deformation was spread over several blocks, it would not be visible without surveying equipment. Image Credit: Joe Dellinger. Photo Date: June 18, 1985 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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