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After Wednesday's Quake, what's next

Posted at 10:00 PM, Mar 18, 2020

SALT LAKE CITY – Wednesday morning’s 5.7 magnitude earthquake provided a startling reminder about the threat quakes pose to the state of Utah.

“It’s the kind of earthquake we like because it draws attention to being prepared and aware,” said Keith Koper, the director of seismograph stations at the University of Utah.

The science behind the threat seems complicated, but can be simplified when looking at the Wasatch mountains.

That mountain range was formed after several earthquakes over millions of years.

“Every time you have a magnitude 7.0 earthquake, the mountains go up a little bit higher,” Koper said. “The motion on any one magnitude 7.0 might be a meter or a few meters. If you wait millions of years, those meters add up and you end up with the Wasatch.”

Researchers have determined those large quakes don’t happen often, but they occur enough to be a threat Utahns should recognize.

“We have geologic evidence of about 20 earthquakes magnitude 7.0 or bigger that happened in the last 10-thousand years,” Koper said. “Utah has a real legitimate seismic hazard.”

Wednesday’s 5.7 magnitude quake was significantly less powerful than what Utah could potentially see in a large earthquake.

“There would be way more damage from a 6.5 than a 5.7,” Koper said. “6.5 would be devastating if it happened right on the Wasatch.”

That’s why being prepared and knowing what to do if the big one hits is vital. But, the prospect of a big quake should not send people into a panic.

“You don’t want to worry people and obsess about this type of thing, but it is a hazard that’s out there,” Koper said. “There’s about a 50 percent probability in the next 50 years that there will be a magnitude 6.5 or bigger along the Wasatch.”

Being aware of the earth’s movement under our feet and dealing with the threat of earthquakes, is just the price Utahns have to pay to live in among the beauty of the Wasatch mountains.