• Earthquake in Southern California raises concerns about ‘The Big One' in Washington

    By: KIRO 7 News Staff

    Updated:

    SEATTLE - A 6.4 magnitude earthquake shook up large parts of the southwest Thursday morning, it was the largest seismic activity registered in Los Angeles since 1999. 

    The tremor originated 7 miles under Ridgecrest, California, located about halfway between Las Vegas and Los Angeles, in Searles Valley, at 10:33 a.m. 

    >> New simulations show how the 'big one' could play out in Seattle

    People reported feeling tremors in Phoenix, Los Angeles, Las Vegas and Mexicali, Mexico. 

    The earthquake lasted about five seconds, following a pair of smaller-magnitude foreshocks 25 minutes prior.

    Plenty of aftershocks were recorded, with the highest magnitude reaching 5.4 Friday morning.  

    According to Harold Tobin, the Director of the Pacific Northwest Seismic Network at the University of Washington, after an earthquake of this extremity, the possibility of an aftershock exceeding 6.4 magnitude isn’t beyond the realm of imagination.

    >> SLIDESHOW: How the 'big one' could play out

    Although earthquakes can’t be predicted in the short term, technology such as ShakeAlert, an app that gives mass warning and alerts of earthquakes to users seconds to tens of seconds in advance, is being tested in Los Angeles County. The app allows users and public services such as public transportation systems to be prepared and take action in the case of a seismic event, potentially saving lives in the process. 

    Right now, ShakeAlert is only available in Los Angeles County and is expected to roll out to the Bay Area and Seattle in the next one to two years, according to Tobin. Those in downtown L.A. experienced intense shaking 45 seconds after the initial quake in Ridgecrest, yet no alert was sent to ShakeAlert users. Tobin said the algorithm used in ShakeAlert didn’t register the tremors experienced in L.A. as strong enough to send a warning to a region that highly populated.

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    Following the largest earthquake in Southern California in the last 20 years, it begs the question of when those up the coast in the Pacific Northwest are expected to experience a considerable seismic event of their own, and how prepared they are in the wake of it.

    “We’d expect that there’s a 15 to 25 percent chance of ‘The Big One,’ or an earthquake of magnitude 9.0 or higher, in Seattle in the next 50 years,” said Tobin.

    The city of Seattle has taken measures to prevent potential seismic damage by updating building construction code for new high-rise towers on top of the demolition of the Alaskan Way Viaduct in April, however many existing structures still remain at risk of earthquake damage due to poor reinforcement from concrete and brick.

    >> Study: Dozens of public school buildings wouldn't be safe after an earthquake

    The last major earthquake in Seattle, the Nisqually quake in 2001 which had a magnitude 6.8, caused several billion dollars in damage. Its devastation was due to its proximity to the highly concentrated Seattle-Tacoma area, yet it was pinpointed 40 miles underground. Tobin claims the damage could’ve been exponentially worse if the quake occurred closer to the surface.

    How can the growing Seattle area prepare for an earthquake greater than magnitude 6.0? The answer, Tobin said, is simple.

    “People should prepare, have a plan in place for your family, and drop, cover and hold,” he said. 


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