Quake Forecast ‘Validated,’ U.S. Agency Claims

There is a 90% chance of a moderately strong earthquake centered near the little Central California community of Parkfield within the next eight years, according to the U.S. Geological Survey in what officials said was the first “validated” forecast of such an event.

The forecast is based on years of study by the U.S. Geological Survey and University of California in and around Parkfield, a farm community of 34 residents located practically on top of the San Andreas Fault.

Geological Survey spokesman Donovan Kelly said Saturday in San Francisco that the forecast of a temblor of 5.5 to 6 on the Richter scale was announced only after an intensive, yearlong review of data gathered by scientists at Parkfield.

He said that although the quake forecast was published a year ago in the Journal of Geological Research, it only became official upon completion of the review by earth science experts from various state and federal agencies, including the National Earthquake Prediction Council.

Parkfield, near Paso Robles about 180 miles north of Los Angeles, has been the focus of earthquake studies because of certain unique geological characteristics. Scientists say it is located at a rupture point on the San Andreas Fault, the 600-mile fault line running from inland Southern California to coastal Northern California.

The fault runs directly under San Francisco, and an 8.7 quake centered there virtually destroyed the city in 1906.

Earthquakes with magnitudes of 5.5 to 6 have occurred at Parkfield approximately every 22 years for more than a century, according to seismologists.