We’ve previously noted the risk of a major earthquake in the Cascadia Subduction Zone, which runs from Vancouver, Canada to Northern California. This week, our friends at Temblor.net cited additional recent studies providing further evidence that such an event is a real threat, and particularly so for the major population centers of Seattle and Portland. Those cities are uniquely at risk of suffering considerable, widespread damage in a mega-quake event.
Seattle and Portland are two of the fastest growing U.S. cities, and currently have metro-wide populations of 3.7 million and 2.4 million, ranking as the 15th and 25th largest metro areas nationally. A major earthquake in the Cascadia Subduction Zone – which stretches for 600 miles – would not necessarily impact either city. But as Temblor explains, there is evidence suggesting both cities are in some of the riskiest territory within the zone, and are prone to particularly dangerous seismic impacts.
According to Temblor, earthquakes within the Cascadia Subduction Zone could reach Magnitude 9, the same severity as the devastating Tohoku Earthquake off the coast of Japan in 2011. And certain indicators studied by seismologists – “locking” and “tremor” – point to Seattle and Portland as being quite susceptible to just such a severe earthquake event. Further, downtown Seattle lies in a lowland basin that makes it particularly vulnerable to shaking damage to buildings in a major earthquake. It also features dozens of office and residential towers in the downtown area, with more being rapidly constructed. In fact, Seattle claims to have led the nation in the most active construction cranes over the last fewyears.
Temblor cites a study by scientists at the University of Southern California and the University of Washington concerning the differences in the degree of swaying or drifting experienced by 4 to 40 story buildings inside the Seattle basin versus outside the basin. Earthquake shaking inside the basin is expected to be stronger and slower, leading to triple the amount of building swaying and likely broader and more severe property damage. Similarly, the Oregon Department of Geology and Mineral Industries posits that a Magnitude 9 earthquake would do at least some damage to nearly 40% of the buildings in the Portland metropolitan area.
What does this mean for insurance industry practitioners? On a professional level, they should be prepared to see a massive volume of property damage claims, including commercial property insurance claims. On a personal level, if they are already dealing with insurance claims or disputes in Portland or Seattle, they should be aware of what to do in an office tower during an earthquake event. Consider these tips from https://www.ready.gov/earthquakes:
Prepare NOW
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Practice Drop, Cover, then Hold On with family and coworkers. Drop to your hands and knees. Cover your head and neck with your arms. Crawl only as far as needed to reach cover from falling materials. Hold on to any sturdy furniture until the shaking stops.
Survive DURING
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Drop, Cover, then Hold On like you practiced. Drop to your hands and knees. Cover your head and neck with your arms. Hold on to any sturdy furniture until the shaking stops. Crawl only if you can reach better cover without going through an area with more debris.
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If inside, stay there until the shaking stops. DO NOT run outside.
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If you are in a high-rise building, expect fire alarms and sprinklers to go off. Do not use elevators.
Be Safe AFTER
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Expect aftershocks to follow the largest shock of an earthquake.
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Check yourself for injury and provide assistance to others if you have training.
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If in a damaged building, go outside and quickly move away from the building.
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Do not enter damaged buildings.
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If you are trapped, cover your mouth. Send a text, bang on a pipe or wall, or use a whistle instead of shouting so that rescuers can locate you.
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If you are in an area that may experience tsunamis, go inland or to higher ground immediately after the shaking stops.
