Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, H.C. Shah, Stanford University. |
The fault scarp from the earthquake of October 10, 1980, at El Asnam, Algeria, shows a 3-m vertical offset on a blind thrust fault. The movement along this fault results from compression. When the thrust layers encounter opposition at depth, they are forced up vertically, producing a vertical scarp. The scarp extends for kilometers along the landscape of El Asnam. This 7.3 magnitude earthquake killed 5,000 people and caused severe damage. Image Credit: H.C. Shah. Stanford University 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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