According to a new study, a potential earthquake on the Hayward Fault could cause almost a quarter of a trillion dollars in damage, of which only a fraction would be insured.

Risk Management Solutions (RMS) has announced the results of a study analyzing the impact of a major earthquake on the Hayward Fault.

The study marks the anniversary of the 1868 Hayward Earthquake - which ruptured the southern section of the fault 140 years ago this month - and was conducted in collaboration with research seismologists led by the U.S. Geological Survey. Results revealed that a magnitude 6.8 earthquake rupturing the Southern Hayward Fault today - based on San Francisco Bay Area's 2008 population and property exposures - would result in economic losses of between $112-$122 billion, of which $11-13 billion would be insured. The study also revealed that a magnitude 7.0 earthquake rupturing the entire length of the Hayward Fault would result in economic losses between $210-$235 billion, with only up to $30 billion likely to be insured.

The Hayward Earthquake occurred on October 21, 1868, rupturing a section of the fault from Fremont to just north of Oakland and causing extensive damage to the small farming communities along the fault. Strong ground shaking and liquefaction also destroyed unreinforced masonry buildings in Oakland and San Francisco.

"More than seven million people now live in the fault zone and surrounding areas - over 25 times the population at the time of the 1868 earthquake," said Dr. Patricia Grossi, senior research scientist at RMS.

"As the southern section of the fault has ruptured, on average, every 140 years for the past 700 years, this particular anniversary highlights the need to continue investing in both short and long-term mitigation as well as preparedness initiatives before the next event occurs."

RMS' loss estimates reflect insurance payments for residential and commercial earthquake coverage, as well as coverage for urban fires that would most likely break out following a major earthquake on the Hayward Fault. They also account for the effects of 'loss amplification,' including economic demand surge (shortages of builders and materials), repair delay inflation (rain damage), claims inflation (difficulties in insurer's policing claims costs), and insurance coverage expansion.

"The impact of a major earthquake on the Hayward Fault is beyond what has been experienced in recent California history, with less than 15% of the losses likely to be covered by insurance," stated Mary Lou Zoback, vice president for earthquake risk applications at RMS. "This is in notable contrast to Hurricane Katrina, for which about 55% of the total economic loss was covered by insurance payments."

She added: "While there has been an enormous public investment in mitigating the impacts to infrastructure of a major Bay Area earthquake over the past twenty years, many residential and commercial buildings remain vulnerable. The low level of earthquake insurance coverage means the massive cost of a Hayward Fault earthquake would largely be borne by the residents and businesses in the area, making rebuilding much more expensive and difficult."

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