Discussion centered around the topic of the “big one” that is expected to hit California in the next 30 years has been ongoing, as research has been conducted in order to assess risk and prepare as much as possible for its arrival. An 8.0 magnitude or higher earthquake along the San Andreas fault would be devastating to the lives of those in the affected areas.
The data released describes the potential damages that California could experience in the case of a massive earthquake. The report’s data estimates the number of homes that could be damaged as well as the potential reconstruction cost for different earthquake scenarios, dependent upon on the location of the rupture area. CoreLogic’s new earthquake hazard system has identified the startling conclusion that a single large earthquake could actually rupture the entire length of the San Andreas fault line, which extends for about 750 miles through California- running from Mendocino County to Riverside County. Previously, other risk models considered the Northern and Southern regions of the San Andreas fault as “independent” of each other. This understanding significantly increases the probability of losses and damage for both Northern and Southern California.
While it is certainly possible for both the Northern and Southern portion of the San Andreas fault to rupture at once, the chances of that happening in our lifetime are quite slim- a USGS researcher states. However, the intent of the CoreLogic study was to theorize about a worst case scenario situation- including multiple earthquake possibilities (LA TIMES).
The financial losses associated with an earthquake of this size are overwhelming. The new estimates put forward by CoreLogic estimate losses of up to $289 billion dollars for an earthquake of 8.3 magnitude, with a larger rupture area than once anticipated. The previous earthquake risk assessment considered the earthquake risk as limited to either areas of Northern California or Southern California, making up two different earthquake scenarios. While the new and revised earthquake risk report considers a full rupture across the entirety of the San Andreas Fault. The previous earthquake risk scenario for a Northern San Andreas rupture estimated the reconstruction cost value at $161 billion. That is more than 100 billion dollars less than the new report estimates for reconstruction cost. As the potential rupture area size increases, so does the number of homes at risk for damage- especially homes in Northern California. The initial risk assessed the number of homes damaged at 1.6 million, while the revised risk estimates more than double that number of homes will be impacted.
The Shakeout Scenario, published by the USGS in 2008, theorized about a potential 7.8 magnitude earthquake that would strike on the far southern portion of the San Andreas fault. This earthquake risk scenario, like CoreLogic’s, assessed the potential property damage and included estimates of the loss of life that may be experienced during a quake of this magnitude and at that specific location. The study initially estimated that there would be approximately 1,800 deaths overall as a result of this quake. Their explanation for such a number is related to the quality of buildings in the area as well as the high risk for fire following the earthquake. Since this report was published, mandatory seismic retrofit ordinances have been passed in cities throughout California.
With this in mind, it is not unreasonable to infer that this number may lessen as residents continue to make seismic improvements on their properties. In fact, it was stated in the ShakeOut scenario report that the number 1,800 was as low as it was because of the proposed improvements that will continue to be made as the retrofit program deadlines approach. The emphasis on seismic retrofit mandates in California can in part be explained by the overwhelming amount of deaths caused by the collapse of soft-story buildings during the 1994 Northridge earthquake, as noted in the Shakeout Scenario report.
It is reassuring that some of California’s cities are taking such significant strides towards greater seismic safety. In the case of “the big one” to come, safer buildings will hopefully lessen the financial damages that California will face and most importantly- lessen the loss of life.
While CoreLogic’s study allows for risk managers to evaluate risk for the purposes of insurance- the implications of this information are much more far reaching. The information this risk assessment provides allows for, among many other things, better preparation for emergency response and improvement to public safety in an earthquake situation.