Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, U.S. Geological Survey. |
Offset of a cement-lined ditch by the left-lateral strike-slip Motagua fault resulting from the earthquake of February 4, 1976, in Guatemala. The Motagua fault is part of the transform fault system between the North American and Caribbean plates and comprises the northern boundary of the Caribbean plate. The North American plate is moving 2.2 cm per year to the west along this boundary. The observed surface rupture along the Motagua fault was 320 km. Displacement across the fault was almost entirely horizontal with the strike-slip component ranging up to 3.4 m and averaging 1.1 m. Vertical displacements were less than 30 percent of the horizontal displacement. Faults caused extensive damage to underground facilities as well as to surface structures. Image Credit: 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. |
|
