The recent events that shook a relatively remote part of the Mojave Desert region of Eastern California provide an acute reminder of the major risk posed by earthquakes in the state. It has been a while now since California experienced a large earthquake, and the main event in this sequence – with a magnitude of Mw7.1, was the most powerful earthquake to occur in the state in twenty years.
Since then, the field of seismology as well as earth scientific measuring capabilities have undergone quite substantial improvements and innovations. Immediately after the start of the sequence, several coordinated efforts from academic, government and engineering organizations resulted in focused field surveys and the installation of additional, more densely spaced instrumentation to monitor seismicity and surface deformation, in and around the epicentral area.
So far, extraordinary amounts of high-quality data have been collected that will undoubtedly provide new insights and understanding of earthquakes in general and earthquake hazard and risk in (Southern) California, in particular. Work on these new data sets has only just started, but what have we learned so far? Here is a summary of observations and interpretations based on various (preliminary) field surveys, reports and briefings.
It is now exactly a quarter of a century, on January 17, 1994, since the last significant U.S. earthquake disaster. A previously unknown blind thrust ruptured beneath Northridge, in the San Fernando Valley north of Los Angeles. Casualties were fortunately modest (57 deaths) because the Mw6.7 shock happened at 4.30 a.m. local time, but the damage was significant – estimated as at least US$30 billion in 1994 prices, as the fault lay directly underneath the city.
Sooner or later California will experience another Mw6.7-7.5 earthquake disaster, in the highly populated San Francisco Bay Area or under sprawling greater Los Angeles. Year-on-year, while the probability rises, the proportion of the affected population with any previous disaster experience dwindles. When it happens, in all senses of the word – it will be a great shock.
One prediction is inevitable: after the next big Bay Area or LA earthquake, there will be large numbers of uninsured homeowners, landlords and small business owners looking for compensation. Given the high deductible and low take-up rates for earthquake insurance, as much as 90 percent of the residential losses will not be covered by insurance payouts: a far higher percentage than in 1994.
And the question is then, will the Federal Government response match that which followed Hurricane Maria, or can we expect it to be more like the aftermath of Hurricane Katrina. Or to put it another way: will California be “Puerto Rico” or “New Orleans”?
There used to be several ways to ensure risk diversification in a California earthquake insurance portfolio. You could select risks on the Peninsula and risks in the East Bay; or select risks in Ventura and Orange counties; or risks in Santa Barbara and Los Angeles counties. Better yet, it was considered that selecting risks in the San Francisco Bay Area and in the Los Angeles region was a perfectly good way of achieving risk diversification. This practice was largely based on an understanding of the spatial correlation of expected loss between counties in California and selecting risks for counties which decreased loss correlations in the insured portfolio.
While California and the large-scale plate motions that it is subjected to have not changed in recent years, the way earthquake sources are modeled has. The two main areas scientists are trying to explore are: first, whether there are preferential locations in a fault network where ruptures are likely to start or stop. The second area examines what the relationship is, if any, between the timing of the latest events on a fault network and the timing of the next event that will overlap with those events. A third avenue of research that is relevant for California is the behavior of aseismic faults — faults that deform without making felt earthquakes, and what happens to them when large ruptures propagate in their direction.
RMS led a study to quantify the impact of these three major modeling assumptions on spatial loss correlations. The study used sixteen county portfolios made using the RMS Industry Exposure Database (2017), and two vintages of source model: the Uniform California Earthquake Rupture Forecast 2 and 3 (UCERF2 and UCERF3). One major conclusion was that new and different risk selection strategies would be required by the spatial loss correlation study to ensure portfolio diversification with the most recent United States Geological Survey (USGS) model (UCERF3) as compared to the previous versions of the model (i.e. UCERF1 or 2).
The rallying cry has sounded — to “close the protection gap”, the difference between what is paid out by insurance and the total cost of some incident or disaster. Here is an issue that can unite and promote the insurance industry, extending benefits to those in peril by expanding the insurance sector. Having ex-post access to funding after a loss, we know, can bring important benefits.
Yet in reality, there is not just one, but three distinct insurance “protection gaps”, each with separate causes and each requiring different remedies. These protection gaps are so different to one another that we should stop treating them as a single category. Lumping them together can cause confusion.
In this series of four blogs, I will explore each of these three distinct gaps, together with the role of protection gap analytics, and the actions we can plan to address these protection gaps.
New findings into the effect of a magnitude 7.0 earthquake originating from the 74 mile-long (119 kilometer) Hayward Fault in the California Bay Area, suggests that fire following earthquake alone could see more than 52,000 single-family homes burn. Earlier this month, the United States Geological Survey (USGS) released new results for their HayWired scenario, a scientifically plausible magnitude 7.0 earthquake on the Hayward fault. The hypothetical HayWired earthquake occurs at 4:18 p.m. on April 18, 2018, the anniversary of the magnitude 7.8 earthquake which struck San Francisco in 1906. The mainshock ruptures the fault along its length for about 52 miles (83 kilometers). The impact of such an event on one of the most densely populated and interconnected areas of the U.S. West Coast — with a population of about seven million people — would be disruptive.
Unlike most U.S. property and casualty insurance, whose take-up rates range from ten percent (California residential earthquake) to greater than 90 percent (for fire insurance), workers’ compensation insurance is required by law. In California, nearly all of the 18.5 million employees across the state are covered by workers’ compensation, whether through an employer’s policy or self-insurance. This enormous exposure generates more than US$18 billion in premium annually, and because California is an “exclusive remedy” state, injuries arising out of and in the course of employment resulting from an earthquake are not excluded. But how can the cost of this obligatory, high risk exposure be measured?