Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, R.C. Bucknam, U.S. Geological Survey. |
This section of the normal fault scarp was produced by the earthquake of October 28, 1983, at Borah Peak, Idaho. It is 678.8 m northwest of the alluvial fan head on Rock Creek. Nearly vertical slickensides on the fault surface are visible on the lower half of the scarp. The scarp is 2.5 m high at this location. The earthquake killed two children in Challis, Idaho, and caused $12.5 million in property damage. Image Credit: R.C. Bucknam. U.S. Geological Survey Through the study of faults and their effects, much can be learned about the size and recurrence intervals of earthquakes. Faults also teach us about crustal movements that have produced mountains and changed continents. Initially a section of Earth's crust may merely bend under pressure to a new position. Or slow movement known as seismic creep may continue unhindered along a fault plane. However stresses often continue to build until they exceed the strength of the rock in that section of crust. The rock then breaks, and an earthquake occurs, sometimes releasing massive amounts of energy. The ensuing earth displacement is known as a fault. This slide set describes the mechanism and types of faulting. It illustrates a variety of fault expressions in natural and manmade features. |
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