A new Berkeley report shows the bill for repairing homes and apartments following the 1994 Northridge earthquake has climbed to $13 billion, many times higher than original estimates.

Based on these new numbers, the amount available to reimburse homeowners through the new California Earthquake Authority signed into law Sept. 27 may be insufficient, say the Berkeley investigators.

Their report, which looks at disasters since 1989, details residential damage from the 6.8 magnitude Northridge earthquake in Southern California. It shows expensive repairs were necessary over a much larger area than previously thought and questions whether Californians will have the means to recover from future earthquakes.

The report was published by the university's California Policy Seminar, with partial funding from the Federal Emergency Management Agency through the California Governor's Office of Emergency Services.

"What we learned is that small damage counts," said Mary C. Comerio, professor of architecture.

"There was damage much, much farther away from the fault than anyone expected. It wasn't catastrophic damage but it was expensive damage -- broken pipes, cracks in the walls, tipped over parking canopies -- as far as 20 to 30 miles from the epicenter."

Comerio said these new findings mean many more Californians will be significantly affected by such disasters than previously thought. The great majority of California's population lives within 20 miles of a fault.

"We're all at risk," Comerio said. "For a while people were saying the damage would be concentrated in an area within a few miles of the fault. That may be true for catastrophic damage, but it is not true for the great majority of earthquake damage."

Without the infusion of capital to make repairs to the housing stock, economists believe regions hit by even a moderate earthquake "will suffer significant economic impacts locally," Comerio said.

Comerio presented the report at an Earthquake Engineering Research Institute conference devoted to discussions of Northridge economic impacts and recovery Oct. 10 and 11 in Pasadena.

The study found most of the repair bills for the Northridge quake were picked up by insurance companies, which greatly underestimated their liability.

Because of this, "we are seeing a desire to exit these markets on the part of the insurance industry," said Comerio.

The report points out that while federal, state and local governments handled immediate response and disaster relief well, no equivalent level of effort went into planning for and financing post-disaster rebuilding.

"Government programs were a small part of residential recovery," said Comerio. "California would be in big trouble without the insurance industry. We will not recover from even a moderate earthquake without insurance."

The new California Earthquake Authority, which will become effective no earlier than Dec. 1, 1996, and is intended to create a $10.5 billion pool of funds for disaster relief, is a good first step, but insufficient based on these new findings, said Comerio.

"The size of the pool has been based on the Northridge experience and that may be insufficient in an event on the Hayward fault or in densely populated areas," she said. Also, "the California Earthquake Authority requires a high level of participation, which may not be met if consumers find the insurance unaffordable."

Currently, insurance rates are set by ZIP code. But the new report shows "the distribution of earthquake damage is a function of ground shaking. The type of ground a house sits on, its configuration and construction quality determine the amount of damage," said Comerio.

Pricing and deductibles for earthquake insurance need to reflect these factors, said Comerio. For instance, the report found homes built prior to 1950 incurred much less damage than those built in the 1960s.

"This is in part because of the style of 1960s houses," said Comerio. "You can expect more problems in houses with huge picture windows, big open-plan living rooms and split-level homes, especially if they sit on poor soil or were not well built."

Co-authors on the California Policy Seminar report, titled "Residential Earthquake Recovery: Improving California's Post-Disaster Rebuilding Policies and Programs," are John D. Landis, professor of city and regional planning, and graduate students Catherine J. Firpo and Juan Pablo Monzon. The California Policy Seminar is a University of California program that applies UC research expertise to state policy concerns.