New data from property information and analytics company CoreLogic, finds that an earthquake along the San Andreas Fault could impact both Northern and South California simultaneously.
Once thought an impossibility, a statewide earthquake could result in 126 percent more property damage, increasing the risks from 1.6 million homes to more than 3.5 million for a magnitude 8.0 or higher earthquake along the fault.
The revised estimate is based on information from the Uniform California Earthquake Rupture Forecast, Version 3, which now depicts the possibility that a single magnitude 8.0 or higher earthquake could travel the full length of the fault from Humboldt County in the north to Imperial County near the Mexican border. Major cities along the fault include the San Francisco Bay area and the Greater Los Angeles area.
The CoreLogic California Earthquake Risk Analysis considers four different earthquake scenarios in California and estimates the number of homes affected and the resulting reconstruction cost value:
Scenario No. 1 – Magnitude 8.3 San Andreas earthquake: Full rupture vs. northern San Andreas rupture.
The longer fault rupture in the new model increases the earthquake risk from 1.6 million homes to 3.5 million, an increase of 126 percent. The estimated reconstruction cost value rises 79 percent from $161 billion to $289 billion.
Scenario No. 2 – Magnitude 8.3 San Andreas earthquake: Full rupture vs. southern San Andreas rupture.
Under the previous Uniform California Earthquake Rupture Forecast, Version 2 model, the number of homes damaged was forecasted at 2.3 million with an estimated reconstruction cost value of $137 billion. The revised earthquake risk shows a 54 percent increase in the number of homes damaged at 3.5 million with reconstruction costs growing 111 percent to $289 billion.
Scenario No. 3 – Magnitude 8.2 San Andreas Fault earthquake.
Even a slightly less intense earthquake would still have a significant impact on homes along the fault line. A magnitude 8.2 earthquake shows that the number of homes damaged still grows 32 percent from 1.9 million to 2.5 million. There would be a 41 percent increase in the estimated reconstruction cost value, which rises from $130 billion to $183 billion.
Scenario No. 4 – Magnitude 8.0 San Andreas Fault earthquake.
The final scenario looks at the impact of an 8.0 magnitude earthquake occurring along the length of the fault line, increasing the number of homes damaged 40 percent from 1.4 million to 2.0 million. The reconstruction costs grow by 73 percent from $83 billion to $145 billion.
The new estimates show larger rupture areas and stronger magnitudes. Irvine, California-bsed CoreLogic says the new science being used identifies three aspects that risk managers should be aware of: A general increase in the frequency of magnitude 5.0 to 6.5 events, a decrease in the frequency of magnitude 6.5 to 7.5 events, and an increase in frequency for events falling in the 7.5 magnitude range or higher. The increase in severity and frequency will require an increase in the amount of capital insurers need to hold in reserve for these losses.
This also affect other factors, such as infrastructure, public safety, utilities, supply chains and transportation for businesses and government entities. Homeowners and business owners must also consider purchasing additional insurance, since earthquake coverage is not included in standard homeowners or commercial liability policies.
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