Earthquake Near Salt Lake City Damages Older Buildings, Rattles Nerves
Officials in Utah are scrambling to assess damages after a 5.7 magnitude earthquake shook Salt Lake City early on March 18. The quake’s epicenter was in the small community of Magna, 10 miles west of the city.
No deaths or injuries have been reported, but flights into Salt Lake International Airport were diverted, and the Utah Transit Authority suspended train service as smaller aftershocks continued into the afternoon. The quake is the largest in the area since a 5.9 tremblor struck southern Utah in 1992.
Nancy Volmer, airport communications director, says that crews are assessing damage from a water main break in Concourse D, which caused some flooding. The airport terminal was evacuated as a precaution.
“We had some ceiling tiles fall out as well, but the airfield is in good shape. Most of the damage beyond that water pipe is cosmetic,” Volmer says. “We are allowing cargo planes to land and take off, and we’re inspecting the building and working to get it back in service.” There was no damage to the runways or taxiways, she says.
Volmer says construction on the new airport terminal on a site directly adjacent to the current facility was suspended for the day and workers were sent home as a precaution. Inspectors are also assessing that facility, which is scheduled to open in October. Work on it was not expected to be delayed more than a day.
The Utah Dept. of Transportation reported 520 bridges “that are in the zone that could have been affected [by the quake],” says UDOT spokesman John Gleason.
“After inspections, we found all of those are in good working order, but we did close one bridge on the Union Park ramp to westbound I-225,” he says. “We just want to get a crane in there and take a closer look at it, just to be sure.”
City and state officials said during a midday press conference that there were 235 power outages in the area, affecting nearly 50,000 people. The most serious problem so far is at a Kennecott refinery west of Salt Lake City. Inspectors and a hazmat team were sent to investigate the release of hydrochloric acid at the site.
Kyle Bennett, spokesperson for Rio Tinto’s Kennecott operations, speaking before discovery of the chemical spill, said work was stopped until further notice. “We were running this morning when the earthquake hit,” he says. “We have temporarily suspended operations for the day. We got all our people out and accounted for.”
“A release of hydrochloric acid occurred at the refinery, and not the Bingham Canyon Mine,” he adds. “As a precautionary measure, all employees were evacuated from the refinery. Unified Fire Authority, in partnership with our emergency response team, has confirmed through remote inspection the release does not pose a risk to public safety.”
Bennett says engineering teams are also assessing conditions in the open-pit mine that has experienced significant landslides in the past.
State and county agencies have groups in the field assessing structures and said they have seen limited seismic damage so far.
“There is some damage on the facades of pre-1975 masonry buildings in the area,” says Rich Thorn, AGC of Utah president and CEO . He says he has not heard about damage or work stoppages on other jobsites in the metro area.
The Church of Jesus Christ of Latter-day Saints reported that the gold trumpet on the Angel Moroni statue perched at the top of the main temple fell off, and “there is minor displacement of some of the temple’s smaller spire stones,” says Daniel Woodruff, a spokesman for the church.
Jerod Johnson, a principal with Salt Lake City-based Reaveley Engineers and Associates, says he inspected the Utah State Capitol and the Salt Lake City and County building not long after the quake. The firm previously designed base isolation and seismic retrofits for both buildings.
“The kinds of behaviors we’re seeing in the aftermath here are consistent with our expectations,” he says. “The state Capitol is designed for a much larger earthquake than this, and the base isolation system does not appear to have mobilized during this event. I saw no damage there.”
Not the Big One
“This was not the big one, but enough to really get our attention,” Johnson adds. “I’d say it’s a small test of how the structural systems are expected to behave. For a lot of state and other buildings we usually design for a level 7 to 7.3 magnitude event.”
Gov. Gary Herbert said in the press conference that the state has already declared a statewide emergency to deal with the coronavirus epidemic. Utah reported 51 COVID-19 cases as of March 17, up from 39 the day before.
Salt Lake City Police Chief Mike Brown said that all of the city’s hospital infrastructure is “up and working. Some may be operating on backup power,” he said. “But all of them are working.” All communications lines are functioning and people should continue to shelter in place, he said.
“No, this is not the big one,” said Steve Cooper, a professor of atmospheric sciences at the University of Utah. He dispelled local rumors about a much larger, possibly 9.0 magnitude quake coming in the near future.
“This one is a moderately sized quake, with only a slightly increased probability of another quake higher than 5.7 happening anytime soon,” he said.
The quake was felt in southern Idaho and as far southwest as Millard County, near the Nevada state line.