Earthquake damage reports keep flowing in as experts examine why some parts of the Salt Lake Valley were hit so hard

(Francisco Kjolseth | The Salt Lake Tribune) Celeste Tunno, a resident of the Western Estates mobile home park in Magna talks about some of the damage sustained to her home following last week's earthquake on Monday, March 23, 2020, as her husband risks shoring up their home with wood blocks despite continued aftershocks.

Five days after a magnitude 5.7 earthquake rocked the Wasatch Front, Salt Lake County residents still were reporting damage as strong aftershocks rumbled and seismologists further explained why some places were hit harder than others.

The Greater Salt Lake Municipal Services District asked those living within its boundaries to go to a form online and submit a report if they suffered damage at their home or business. The district covers Magna, near the epicenter and the township hardest hit by Wednesday’s quake, as well as Kearns, Copperton, White City and other unincorporated parts of Salt Lake County.

The online form can be found at https://arcg.is/1uGXee. Residents also can report damage by calling 385-468-6723 during business hours or leave a message at 385-468-6690 after 5 p.m.

A map of the Greater Salt Lake Municipal Services District can be found at https://msd.utah.gov/about/map. If you don’t live in the district, damage should be reported to your city government.

(Francisco Kjolseth | The Salt Lake Tribune) Antonio Tunno risks going under his home in the Western Estates mobile home park in Magna on Monday, March 23, 2020, for the first time since last week's earthquake despite feeling an aftershock earlier in the morning. Using wood blocks, Tunno was trying to shore up his home after multiple jacks under his home had failed, much like many of his surrounding neighbors.

Maridene Alexander, communications manager for the district, said the aftershocks that have continued rattling the county since Wednesday may have caused additional damage. According to the U.S. Geological Survey, 367 aftershocks have been recorded as of 2 p.m. Monday, with 29 exceeding magnitude 3.

The pace of aftershocks slowed for the first three days after the initial quake, then a sudden wave was unleashed Sunday night, with one approaching magnitude 4 and felt by many in Salt Lake City.

Alexander asked residents to inspect buildings for cracks in masonry, foundations, drywall and piping.

“We just want them to look around their homes or businesses for any changes," Alexander said.

Building owners should be especially concerned about brick chimneys, she said. Inspect the chimneys for loose bricks. If the chimney provides ventilation for a fireplace or appliances such as furnaces or water heaters, make sure it still vents.

Alexander also encouraged building owners to ensure they have a working carbon monoxide detector.

Salt Lake City’s 126-year-old City Hall remained closed Monday. It could reopen soon.

Lindsey Nikola, the communications director for the mayor’s office, said the landmark building is structurally sound. Repair crews are fixing plaster that came loose from the interior and ensuring that elevators pass their tests.

“Things are looking really good,” Nikola said, “and we’re pleased with where it’s at.”

Also closed is the 110-year-old Rio Grande Depot a few blocks west of City Hall. The historic railway station houses the Utah Department of Heritage and Arts, along with its gallery, priceless archives of documents and photographs, research library and a restaurant.

“There was some structural damage, mostly on the south end, mostly stuff that had come off walls,” said department spokesman Josh Loftin. “It could cause injury if there was a significant aftershock. The earthquake cracked walls and knocked plaster off. In doing so, it released a bunch of lead paint dust. They need to mitigate the lead dust so they can take a better look at the interior walls.”

It will take at least a few months to complete repairs, he said, before staff and the public can resume using the building.

(Francisco Kjolseth | The Salt Lake Tribune) Some clean up has taken place along historic Main street in Magna on Monday, March 23, 2020, following last week's earthquake while many other areas remain the same.

Salt Lake City’s historic buildings west of downtown fared worse than the older masonry buildings east of State Street. This difference was likely the result of the deeper sediment deposits in that part of the Salt Lake Valley, which are more prone to liquefaction in an earthquake and more likely to amplify shockwaves, according to seismologists.

Three key factors determine the extent of damage to a particular building: proximity to the quake’s epicenter, in this case about 12 miles west of downtown; the building’s construction; and the type of ground it’s built on.

Most of Salt Lake City’s historic buildings that have not undergone a seismic retrofit are constructed of unreinforced masonry, which doesn’t hold up well with side-to-side shaking associated with earthquakes, according to Jamie Farrell of the University of Utah Seismograph Stations. But the valley’s sedimentation could be the biggest factor.

“The valley is this deep basin full of sediments, coming out of the mountains, sediments from old Lake Bonneville,” which covered much of northwest Utah 14,000 years ago. “Those sediments tend to amplify shaking,” Farrell said. “In the Avenues and east bench, we are sitting more on bedrock that don’t experience as much ground shaking.”

(Christopher Cherrington | The Salt Lake Tribune)

An online dashboard for earthquake damage reports within the county’s Municipal Services District had 260 entries as of 4:30 p.m. Monday. Many of those reports are coming from residents outside the service district and as far away as Bountiful, which sits in Davis County.

Of the reports from residents within the service district, inspectors had confirmed 27 structures have “Condition Issues,” according to the dashboard. Inspectors confirmed another 22 “Nonstructural Issues,” which can include damage to fences or driveways.

Not every damage report has been confirmed yet. Inspectors are triaging site visits based on the extent of the damage reported.

It seems not all the damage has been reported to the service district website. Greg Schulz, administrator of the Magna Metro Township, on Monday said many buildings on Magna’s historic Main Street suffered damage.

Magna is home to 24 of the 126 historic buildings whose earthquake damage has been documented by the Utah Division of State History.

Schulz said Magna’s numbers could change as owners have structural engineers make assessments.

Some inspections and restorations have been slowed by aftershocks. The latest, a magnitude 3.1, arrived about 8:13 a.m. Monday.

“You send them back in" to a damaged building, Schulz said, "and you have another bumper, and all the sudden you [could] have casualties.”

Schulz estimated 30 or 40 people have been displaced in Magna. He said many of those were tenants of the Panama Building. It’s one of the historic buildings from Magna’s mining days that has been converted into apartments and office space. The structure has not yet reopened.