Research helps bring earthquake risks into focusReprints
While scientists cannot predict earthquakes, seismologists and research analysts say they are getting a clearer picture of earthquake activity.
A study of the San Andreas fault released on March 2 by the U.S. Geological Survey found evidence that large earthquakes — roughly magnitude 7.0 to magnitude 7.5 — have occurred near Tejon Pass in Kern County on average every 100 years.
The Fort Tejon earthquake of 1857 was the last large earthquake in the area where the San Andreas Fault broke the surface continuously for 220 to 250 miles, according to the Southern California Earthquake Data Center.
“It’s important a business owner knows that statistically we’re past the average,” said Kate Scharer, Pasadena, California-based research geologist at the USGS and lead author of the report. “It’s up to all of us to make sure we’re prepared at home to help our neighbors and our family, and if you own a business you want to think about planning for major events like this and how you deal with it.”
Another study, led by the Scripps Institution of Oceanography at the University of California San Diego and published online on March 7, found the Newport-Inglewood and Rose Canyon faults, which had been considered separate systems, are actually one continuous fault system running mostly offshore from San Diego Bay to Seal Beach in Orange County, then onto land through the Los Angeles basin.
The fault system is capable of producing up to magnitude-7.3 earthquakes if the offshore segments rupture and a 7.4-magnitude quake if the southern onshore segment also ruptures, the report said, noting that “the fault zone poses a significant hazard to coastal Southern California because of its close proximity to some of the most densely populated regions of North America, such as San Diego, Orange and Los Angeles counties, as well as Tijuana, Mexico.”
Maiclaire Bolton, Oakland, California-based seismologist and senior product manager with CoreLogic Inc., said that modeling of the two faults indicates that, depending upon the magnitude and location of the earthquake, insured losses from a magnitude-7.2 to -7.5 earthquake could range from $20 billion to $90 billion.
“That’s why it’s so important to use a risk model, because it can show you all the different potential events that can happen and not just focus on one event,” Ms. Bolton said. “A risk model is important because it doesn’t just take the hazard, but it factors in what are the buildings within the specific events that can happen and then what’s the damageability of them.”
A spokeswoman for the California Department of Insurance said about 8% of businesses in the state had earthquake insurance as of 2015, the year for which the most recent data was available. These were admitted carriers, as the surplus lines are not required to report to the department, she said.
Andrew O’Donnell, senior engineer at AIR Worldwide in Boston, said engineers and seismologists obtain information from GPS stations and GPS recording devices to get a sense of how tectonic plates are moving.
“If we observe there’s not much movement where there should be,” he said, “we can kind of point where there’s likely to be a release of stress.”
He noted that AIR’s seismologists and geophysicists identified an area that had been accumulating a great deal of strain prior to last year’s earthquake in Ecuador that killed 676 people.
“Before that earthquake occurred,” he said, “we had made that kind of prediction, and to see that play out in real life was fascinating from a research perspective. It gives a little bit more credence to the methodology that we not only employ at AIR, but also kind of how it’s thought about in the general scientific community because there’s still a bit of debate about how valid this approach is.”
Janet Ruiz, San Francisco area-based California representative for the Insurance Information Institute, advises businesses to determine the condition of their buildings and decide if they are adequately insured.
“A lot of businesses have their regular insurance,” she said, “but they have to think about do they have earthquake insurance and does it make it sense. And if you’re anywhere near the fault line, you should be definitely planning it.”
Analysts acknowledged that predicting earthquakes is not an exact science.
“We’ll never be able to say that a magnitude-7 earthquake is going to hit this location on Tuesday at 3 p.m.,” said Ms. Bolton of CoreLogic. “It just doesn’t work like that. But I think having an understanding of how frequently big earthquakes happened, where they can happen and what the damage potential of those are is really the first step for risk managers, whether they be in the insurance industry or anywhere in public safety or emergency planning, to be able to understand how to appropriately prepare for an earthquake.”