North Coast Was Already Reeling Before Quakes Hit : Economy: Temblors hit an area weakened by soaring unemployment and cutbacks in key industries.

EUREKA, Calif. —  For the isolated and economically troubled North Coast, the powerful weekend earthquakes were like being kicked when you were down. Three times. Hard.

More economic woes were the last thing that people in the redwood country wanted or needed, to go with a soaring unemployment rate, swelling welfare rolls and the recent news that the commercial salmon fishing season off the coast was all but canceled for lack of fish.

But even so, on Monday morning businesses and residents began digging out in earnest.

In Ferndale, glaziers replaced windows in the quaint downtown business district and contractors prepared estimates for putting dozens of quake-damaged Victorian homes back on their foundations. Ten miles to the south, in gritty Rio Dell, workers and shopkeepers stripped cracked plaster from storefronts.

“We’re going to redo the whole front,” said Lillie Barker, owner of Barkers Market. “We lost maybe three-quarters of our inventory, and we had over $90,000 on the shelves.”

What remained unclear was how financially strapped Humboldt County will pay for the estimated $51 million in damage to businesses, homes, roads and bridges caused by the three magnitude 6.0-plus temblors.

Some homeowners will be eligible for as much as $15,000 in rebuilding funds from the state’s new earthquake insurance program, which went into effect in January. And some, though not many, will be covered by private insurance policies.

In the meantime, local, state and federal officials were completing damage assessments in hopes that President Bush would today declare the earthquake zone a federal disaster area, making residents and store owners eligible for low-interest loans and other government assistance.

But officials in Humboldt County expressed concern over the share of the burden that will potentially have to be borne locally. The county was reeling from a long-term decline in the once-robust timber industry and the latest wallop by federal officials who imposed unprecedented limits on the salmon harvest.

Some saw the quakes--a magnitude 6.9 shaker on Saturday morning, followed by a pair of Sunday morning aftershocks measuring 6.0 and 6.5--as a divine insult added to an ongoing injury.

“We’re down and then we’re being kicked,” said County Supervisor Harry Pritchard, whose district includes some of the towns hardest hit by the quakes. “The federal government is down on us,” he said. “The state government is down on us. And now God is down on us.”

Unemployment in Humboldt County hit 11.9% in February, compared to a statewide rate of 8.7%. In the last year, food stamp applications have increased 25%.

On Monday, Pacific Lumber Co., the county’s largest private employer, was forced to shut down the two sawmills in its company-owned town of Scotia because of earthquake damage. Employees reporting for duty were put to work restacking tumbled boards and moving machinery that had been jostled by the tremors. The company has 700 employees in Scotia.

Company spokeswoman Mary Bullwinkel said that executives hope to avoid layoffs but that it could be weeks before the Scotia mills are operating again. Two other mills--in Fortuna and Carlotta--that employ about 550 workers were unaffected and are operating.

Meanwhile, earthquake scientists from the U.S. Geological Survey and Stanford University said Monday that the aftershocks occurred on a different fault and radiated a more damaging form of energy than the earlier, more powerful main quake.

Greg Beroza, professor of geophysics at Stanford, said that because of its higher frequency energy waves, the 6.5 aftershock at about 4 a.m. Sunday did much more damage than Saturday’s 6.9 main shock.

This aftershock also was felt much more strongly in the San Francisco Bay Area, 250 miles away, than the main shock, Beroza said.

Beroza and David Oppenheimer, a seismologist with the U.S. Geological Survey in Menlo Park, said that the 6.9 main shock occurred on an unnamed fault on the edge of the Gorda tectonic plate and was a thrust earthquake in which the Gorda plate forced its way under the North American plate.

Tectonic plates are large land masses that float on the molten core of the Earth. Three plates, the Gorda, North American and Pacific, come together in the general vicinity of the weekend earthquakes, although their exact boundaries require more research, the scientists said.

Beroza and Oppenheimer said that stress transferred from the main shock, centered just onshore near the village of Petrolia, south of Eureka, probably generated the aftershocks on another unnamed fault on the Gorda plate, 15 miles out in the Pacific, that had not moved in the first earthquake.

The aftershocks were more common strike-slip earthquakes, where the two sides of the fault slide past each other horizontally, they said.

“The second (more powerful) aftershock had a very short duration, consistent with a high rupture velocity or (with) the slip happening over a small fault rather than a large one,” Beroza said. “It had exactly those high frequencies that people perceive, and that damage buildings.

“It seems by looking at the records we have that the 6.5 aftershock had at least as much and likely more damage potential as the main shock,” Beroza added.

The aftershocks may have conveyed their energy much more directly at the damaged towns of Ferndale, Scotia and Rio Dell than the main shock, although the aftershocks were centered farther away, Beroza said.

Oppenheimer said that the “radically different earthquakes” of Saturday and Sunday point out the difficulty earthquake scientists face in predicting relative ground motion and amounts of damage in locales even if they ever become able to predict earthquakes.

Times staff writers Paul Feldman and Ken Reich in Los Angeles also contributed to this story.