Analysis: California quake hit right spot

By HIL ANDERSON  |  Dec. 22, 2003 at 7:14 PM
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LOS ANGELES, Dec. 22 (UPI) -- It isn't often that California can say it came away relatively unscathed after being rocked by an earthquake that measures 6.5 on the Richter scale.

Even as rescue crews continued digging through heaps of broken bricks in downtown Paso Robles looking for trapped Christmas shoppers, it appeared that the quake would not be the immense tragedy it could have been had it struck in one of the state's major urban areas.

"If you look at the Northridge earthquake, it was a hair larger than this one and it was a $40 billion (in damage) event," said Bob Stein of the U.S. Geological Survey office in Menlo Park, Calif. "If you take this earthquake and put it out here and it may be an event in which the damage is measured in the millions of dollars."

The sadness of the three deaths that were reported in Monday's quake was magnified by their occurrence so near Christmas, however there was no denying the overall sense of relief in California that it had not been worse.

"So far, there has not been much to report other than we have had a typical 6.5 magnitude quake that fortunately occurred far from densely populated areas," Stein summed up.

Monday's quake came almost 10 years after the Jan. 17, 1994, Northridge quake that measured 6.7 on the Richter scale but left 57 people dead, around 1,500 injured and extensive property damage in the crowded San Fernando Valley area of Los Angeles.

The 1989 Loma Prieta quake that struck the San Francisco Bay Area measured 7.0 on the Richter scale and caused 62 deaths and around $10 billion in damage.

By contrast, Monday's event rocked a largely rural area along the scenic California coast roughly midway between Los Angeles and the San Francisco Bay Area.

Preliminary indications were that the worst of the damage was in the town of Paso Robles, a town of around 25,000 located in the wine country about 25 miles north of San Luis Obispo. The shaking caused at least two of the downtown area's older brick buildings to collapse, however a police officer said the strength of the quake built slowly and gave shoppers just enough time to get into the open.

"The downtown was packed," police Sgt. Bob Adams told Los Angeles television station KNBC. "Initially it was a rolling motion so you realized an earthquake was coming, and then it got really violent."

The quake shook up a lot of residents, however the structural damage was scattered and fairly light. Some power outages were reported and rockslides temporarily blocked roads in the area. The nearby Diablo Canyon nuclear powered plant shook but weathered the tremor with no reported damage and continued to generate electricity without interruption.

There was more to the light toll Monday other than the scarcity of people and buildings. Although the shaking was felt hundreds of miles away, it appeared the major force of the tremor was confined to the region around the epicenter.

The series of aftershocks that began almost immediately and continued into the night appeared to be occurring generally in an easterly direction along the fault line rather than traveling north toward the Bay Area or south toward the great Los Angeles sprawl.

The fault line where the quake struck connects to the San Andreas Fault, which runs nearly the entire length of California and is considered by seismologists as a likely site for "The Big One."

According to Stein, Monday's quake was too far from the San Andreas to trigger a larger event, and had the kind of geological characteristics that can, in effect, smother the main force of the shaking.

"We're a long way from that particular part of the (San Andreas) fault and the chances that this earthquake would trigger something that extended all the way to the Bay are remote, based on the kind of fault this is," Stein explained. "It's a little too grungy and jagged to produce a 'through-going' rupture like the San Andreas might."

"We want to watch whether the San Andreas in the central part of California changes its behavior," he said. "That's an area that has produced magnitude 6 earthquakes every 20-30 years for almost 100 years."

The impact Monday's earthquake had on the dangerous San Andreas fault will be left to the scientists as the folks in San Luis Obispo County clean up, tally their losses and thank goodness that Christmas 2003 didn't turn out to be any worse.

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