Home computer network urged for San Francisco quake detection


LOS ANGELES -- Two earthquake experts have proposed that residents of the San Francisco Bay area be asked to participate in a huge quake-detection network, using personal computers hooked up to backyard measuring devices.

"There are at least 100,000 home computers in the Bay area," said Dr. Edward Cranswick, a seismologist at the U.S. Geological Survey in Golden, Colo. "If just 1 percent of them hooked up into a centralized network, we could get seismological information from where the people live."

Dr. Cranswick presented his idea at the fall meeting of the American Geophysical Union in San Francisco earlier this month. His collaborator is Robert Banfill, who provides personal computer programs for geologists through his company, Small Systems Support in Big Water, Utah.

People would volunteer to participate, Dr. Cranswick said. They would be required to purchase an instrument and a computer programthat would cost a total of about $500, he said. The instrument, an accelerometer, would be placed in the back yard and connected by cable to a box attached to the computer indoors.

The accelerometer would automatically measure the acceleration and velocity of all ground motions, said Dr. Cranswick, including earthquakes too small to be felt.

Data would be fed into the box and automatically sent over phone lines to a central computer at Geological Survey offices in Menlo Park.

Seismologists would gain a wealth of information, Dr. Cranswick said. It is known that houses in the same neighborhood respond differently to ground shaking, depending on local soil conditions. The dense network would provide scientists with insights into these differences.

Small earthquakes' patterns might serve as precursors to larger events. And when larger faults ruptured, the home computer data would provide a better picture of ground motion than has ever been captured, Dr. Cranswick said.

While the system would work automatically, Dr. Cranswick said volunteers would have to check that the instruments were in working order. It would be no more difficult than monitoring a rain gauge, he said.

Members could put data from their backyard instruments and the network into their computers.

Dr. Cranswick said the idea was inspired in part by events in Haicheng, China, 15 years ago, when peasants reported observations about odd behavior by animals and changing water levels in wells just before a serious earthquake struck.

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