SCIENCE / MEDICINE : A 6.0 Prediction for Parkfield : Experts Say Major Quake Will Hit Town By 1993

In 1985, the U.S. Geological Survey issued what it calls “the first officially accepted earthquake prediction in the United States.”

The prediction said an earthquake registering 6.0 on the Richter scale is expected to occur along the San Andreas Fault near the Monterey County town of Parkfield before 1993.

An earthquake of a similar magnitude has occurred in that area about every 22 years, the U.S. Geological Survey said. A stronger earthquake, perhaps a magnitude 7, also is possible, according to the agency.

The Geological Survey and the California Division of Mines and Geology have installed sophisticated geophysical instruments--including laser beams that can detect the slightest earth movement--in the Parkfield area in hopes of detecting geological signs of an impending quake.

The idea is for the Geological Survey to issue a “short-term” alert to the California Office of Emergency Services up to 72 hours in advance of an anticipated earthquake.

Upon such an alert, the Office of Emergency Services is to transmit a warning to the public through county offices of emergency services and through the news media.

Although the immediate Parkfield area is sparsely populated ranchland--the town has just 34 residents--the effects of a large earthquake centered there nevertheless could be far-reaching, affecting populated areas like San Francisco and Los Angeles, according to the Geological Survey.