Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, G. Reagor, U.S. Geological Survey. |
The magnitude 7.2 earthquake of October 28, 1983, near Borah Peak, Idaho, produced this fault. The scarp and fracture zone are located on Rock Creek, near Dickey, Idaho, and Double Springs Pass Road. The wooden pole is 1.9 m high. This normal fault shows characteristics of oblique-slip, where there is both vertical and horizontal displacement. The horizontal movement is left-lateral. The fault scarp extended for more than 35 km, with vertical displacements up to 2.5 m observed between MacKay and Challis, Idaho. Image Credit: G. Reagor. 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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