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Images: Earthshaking Events

Without warning, a magnitude 7.8 earthquake struck the city of Tangshan in China, killing 242,769 people and destroying 90 percent of the city's buildings. A similar earthquake struck 17 months earlier about 280 miles northeast near Haicheng. But a series of smaller foreshocks provoked Chinese officials to issue warnings urging people to remain outdoors, and only 1,328 people died. (Courtesy: China Stock Photo Agency)

Two major earthquakes occurred 17 months apart in the mid-1970s near the cities of Haicheng and Tangshan in northern China. (Illustration by Jack Cook, WHOI Graphic Services)

Faults on land, like the San Andreas Fault near Palmdale, California (top), are similar to those in the ocean, like the Atlantis Transform Fault in the Atlantic Ocean (bottom, three times vertical exaggeration). But in many ways, oceanic faults are easier to study and offer the potential to discover fundamental aspects about earthquakes that are applicable to land. (Top credit: NASA/JPL/NIMA; bottom credit: Tom Reed, University of Hawaii, and Brian Tucholke, WHOI)

WHOI geophysicist Jian Lin stands near the plainly visible ruptured surface of the Pleasant Valley Fault in Nevada, which caused a magnitude 7.1 earthquake in 1954. (Photo courtesy of G. Valensis/Italian Institute of Seismology)

A satellite image shows a portion of the San Andreas Fault and smaller neighboring faults (white lines) in southern California. (Courtesy: NASA/JPL/NIMA)

Since 1992, a sequence of four moderate to major earthquakes has occurred in sparsely populated places in the Mojave Desert, near the towns of Joshua Tree, Landers, Big Bear, and Hector Mine. (Courtesy of Andrew Freed, Purdue University)

Computer models simulated how the Joshua Tree, Landers, Big Bear, and Hector Mine quakes alleviated stress in some places (blue areas) and transferred and increased stress (red areas) to adjacent regions. In a domino-like effect, strain can "creep" through the crust, interact with neighboring faults, and trigger another earthquake elsewhere. Scientists believe that the Landers and Hector Mine quake sequence together have shifted stress toward the San Bernadino Mountain segment of the San Andreas Fault and increased the likelihood of a quake there. (Courtesy of Jian Lin, WHOI)

In early May of 1998, hydrophones began to record a flurry of small earthquakes near the Siqueiros Transform Fault, an 80-mile fault sandwiched between two volcanic mid-ocean ridges in the Pacific Ocean. The flurry culminated in a magnitude 5.8 quake on May 10. This was followed by another flurry of smaller quakes in an outlying area about 20 kilometers away and another magnitude 5.8 quake only 18 hours after the first one. New findings like this reinvigorate hope that further understanding of foreshocks can provide warning of larger quakes, at least in some places on Earth.

A computer model simulated how stress on rocks is transferred in a region. At left, rocks on either side of a fault push against each other, building up stress. At right, the stress overcomes friction, and the fault ruptures violently in an earthquake. In the aftermath, strain is alleviated in some areas (blue) and transferred and increased to other neighboring areas (red). (Courtesy of Ross Stein, USGS)