Big Quakes on San Diego Fault Spread Over Thousands of Years : SCIENCE FILE / An exploration of issues and trends affecting science, medicine and the environment

<i> From Times staff and wire reports</i>

Strong earthquakes occur along San Diego’s most significant fault, the Rose Canyon Fault, at least every 4,000 years, and perhaps as frequently as every 1,000 years, according to Scott C. Lindvall, a geologist with Harza/LRB, a consulting firm in Los Angeles. The conclusion is based on evidence, reported in the December Journal of Geophysical Research, that the Rose Canyon Fault ruptured at least three times in the last 8,100 years.

Evidence showing the quakes to be spread out over thousands of years could be good news for San Diego residents worried about the next quake, Lindvall said. The most recent quake on the fault apparently occurred about 400 to 600 years ago, he said.