Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, Clifford E. Harwood. |
View to the east of the Highway 14 road cut that transects the San Andreas fault zone. Since 1994, California Transportation has cut smooth the portion of the San Andreas that bisects Highway 14, creating a spectacular view of the compressional forces in the area. The Northridge, California, earthquake (January 17, 1994) narrowed the San Fernando Valley by 9 cm and raised the top of the hills to the north by approximately 38 cm. The earthquake resulted in increased compression along the San Andreas fault. In this view, a subsidiary fault transects the fold in the right half of the photo. Image Credit: Clifford E. Harwood. 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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