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Capital Weather Gang

5.7-magnitude earthquake strikes Salt Lake City

The international airport in Utah’s capital was evacuated for hours as aftershocks continued

By
March 18, 2020 at 6:39 p.m. EDT
A computer-generated map illustrates where residents reported shaking associated with a 5.7-magnitude earthquake near Salt Lake City on Wednesday morning. (USGS)

A 5.7-magnitude earthquake struck near Salt Lake City on Wednesday, damaging buildings, causing thousands of power outages and upending operations at the airport for several hours.

The earthquake struck around 7 a.m., its epicenter located about four miles west-southwest of Salt Lake City International Airport. Heavy shaking was felt across north-central Utah west of the Wasatch mountains.

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There were no reports of any serious injuries, though many people were evacuated from the airport and the Federal Aviation Administration issued a ground stop for all inbound flights for several hours. Video emerged on social media of damaged pipes gushing water from the ceiling inside a terminal.

The airport was deemed safe and passengers were allowed back just after 1 p.m. The damaged water pipes also were promptly repaired.

A 5.7-magnitude earthquake hit near Salt Lake City the morning of March 18. Within an hour of the initial quake, at least a dozen aftershocks were reported. (Video: The Washington Post)

For much of the morning, though, the airport urged passengers to stay away.

Within three hours of the initial quake, nearly two dozen aftershocks greater than 3.0 in magnitude struck in the immediate vicinity.

According to the U.S. Geological Survey, there is a roughly 1 in 5 chance of an aftershock greater than 5.0 in magnitude occurring.

The earthquake was shallow, occurring only about six or seven miles below the surface, which may have maximized shaking at the surface.

According to Utah’s Division of Emergency Management, it was the strongest earthquake to strike the state since 1992.

Rocky Mountain Power reported 55,000 customers without power in the Salt Lake region after the quake.

There also were reports of structural damage. Cracked walls, toppled furniture and other minor damage were reported at the homes of many residents across the state capital.

Initial data suggested the earthquake was associated with “normal faulting,” which occurs when one tectonic plate or fault slides down the side of another.

In addition, there was probably some strike-slipping, which means one fault slid a bit past the other side-to-side.

The quake is likely to have occurred along the Wasatch fault. It parallels the Wasatch Range, which is no surprise, considering the mountains were formed by it. The plate to the east rises, while that to the west dips below.

According to the USGS, the Wasatch fault zone can be divided into 10 smaller segments of faulting, about half of which have been active for 10,000 years. The USGS estimates that those segments produce quakes reaching 7.0 in magnitude about every 900 to 1,300 years.

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