Oct. 20, 2022 at 10:20 a.m. local time will serve as the Great ShakeOut Day across the country. Participants take part in earthquake drills, including the actions of "Drop, Cover and Hold On," as if the ground was actually shaking.
Started in 2008 in California, the 'Great ShakeOut' has become a global initiative encouraging people and businesses to educate themselves on their earthquake risk, create a disaster plan and update emergency preparedness kits.
Missouri is one of those states joining in the Central U.S. ShakeOut. According to shakeout.org, over 350,000 Missourians have registered to participate, along with over 44 million pledging worldwide.
Missouri, not usually associated with big fault zones like California, has had its fair share of earthquakes. In fact, one happened as recently as April 29, 2022, when a 2.8 magnitude had the ground shaking near Valley Park in St. Louis County.
No damage was reported, but people all over the county felt shaking.
According to the U.S. Geological Survey (USGS) perceived shaking chart, a magnitude earthquake of 3.9 or less would elicit light shaking with no potential damage. That correlates with what occurred back in April in Valley Park.
This quake near St. Louis didn’t occur along a fault and, according to Washington University geophysics professor Michael Wysession, this quake was likely because of the North American plate drifting westward over a “lumpy mantle,” causing flexing and bending within the plate.
He adds that it “could also have been attributed to a weak spot on the North American plate.”
A fault zone exists in Missouri. It's called the New Madrid Seismic Zone and is in southern Missouri near the "boot heel." The early 1800s saw the strongest quakes in this region, with estimations of magnitude around 6.7–7.2, although seismometers didn’t exist until late 1800s.
According to Wysession, the zone is quite new, having only been around for 200 years. As for whether we can expect earthquakes from this zone, he says “earthquakes tend to follow a fractal dimension of one, for the way we determine the magnitude scale.”
He explains that "for the last 150 years along New Madrid, we’ve had one magnitude 6, 10 magnitude 5s, 100 magnitude 4s. If you come up to the St. Louis region, where the April 2022 quake occurred, we had only three other earthquakes in that region over the last 40 years, all around 2.8.”
Based on these statistics, we can expect a minor earthquake once every decade.
While the threat remains low for a big earthquake in the St. Louis area, it doesn’t mean the risk is zero. Federal, state and local emergency management experts have all agreed upon the “Drop, Cover and Hold On” technique during an earthquake to save lives and reduce injury.
If you feel shaking, DROP where you are on your hands and knees.
COVER your head and neck with one arm and hand. If possible, crawl under a sturdy table or desk for shelter. If no shelter is available, crawl next to an interior wall.
HOLD ON until the shake ceases. If under a shelter, hold on to it and be prepared to move if it shifts. If you're not under something, hold on to your head and neck with both arms and hands. The website also has accessibility actions to take if one cannot drop to the ground.
To register as a participant in the Great ShakeOut, go here.
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