Next big Wasatch Fault earthquake could damage homes, schools

Tuesday , October 17, 2017 - 5:30 AM

LEIA LARSEN, Standard-Examiner Staff

There are reminders everywhere — the devastation in Mexico City, the drills in schools, the dramatic Wasatch Mountains and the many scarps in the foothills. 

Northern Utah is due for a big earthquake, the kind that devastates. The kind that could kill 2,000 people, injure more than 7,000 and displace tens of thousands more.

While we haven’t seen an earthquake of this magnitude since Brigham Young moved into the Salt Lake Valley and decided to put down roots, there’s a record of them all along the Wasatch Fault, the seismic belt that forms the eastern edge of the Great Basin and runs east of its namesake mountains from Brigham City to Nephi. Geologists have found evidence of 22 massive earthquakes on this fault in the last 6,000 years and it’s still seismically active.

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This year, the Working Group on Utah Earthquake Probabilities calculated the region’s prospects for the next “really big one.” The Wasatch Front has a 43 percent probability of one or more earthquakes of a 6.75 magnitude and a 57 percent probability for a 6.0 magnitude quake.

“It takes a magnitude 6.5 to break the earth’s surface,” said Adam McKean, who maps geologic hazards for the Utah Geological Survey. “We could expect a magnitude in the 7.1 or 7.5 range — 7.1 is what Mexico just experienced. That would destroy a large part of Salt Lake.”

The problem is, Northern Utah hasn’t seen an earthquake that big since people started building homes, schools and business right along the Wasatch Fault. The closest was the 1934 earthquake in Hansel Valley, a 6.6 magnitude quake on the north shore of the Great Salt Lake that impacted a wide area. About 45 miles to the east, the three-story agricultural building at Utah State University split. Two other public buildings in Logan had to be abandoned. Five aftershocks rumbled from the area over eight weeks. 

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Along the Wasatch Front, chimneys collapsed and walls cracked. Two people died. 

Utahns see news stories about earthquakes and warnings from geologists all the time. But when an earthquake of the same magnitude as Hansel Valley — or bigger — inevitably hits closer to home, will they be prepared?

“A lot of people in Utah are aware of the earthquake hazard ... but a lot of people don’t take it seriously enough to put some serious resources toward getting ready for it,” said Jim Pechmann, a seismologist at the University of Utah Seismograph Stations and a member of the Working Group on Utah Earthquake Probabilities. “This is going to happen some day. It’s a big problem.”

When the quake hits home

Earthquake experts in Utah all seem to agree: There are a lot of homes that are dangerously unprepared for ground shaking. 

“When the pioneers moved in, and Ogden and other cities have the same issues, they built a lot of brick homes before building code said ‘no, we’re in earthquake country, we really shouldn’t build homes that are unreinforced,’” McKean said. “They’re beautiful homes, they have lots of character, they’re pretty bad for earthquakes.”

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When the earth starts moving, these unreinforced structures start dropping their bricks. The roofs usually aren’t connected to the walls and the walls usually aren’t connected to the foundation, which means they can collapse, McKean said.

Most brick buildings built before 1975 in Utah are considered unreinforced masonry structures — they don’t have steel reinforcing the bricks. 

FEMA and the Utah Seismic Safety Commission have comes up with guidelines for reinforcing these old homes to make them safer, but those upgrades don’t come cheap. It’s about $4,000 to $7,000 for a medium-sized house with a crawl space, according to EarthquakeSafety.com, a California-based residential retrofitting contractor. For larger homes or those with basements, retrofits can cost $10,000 or more. 

Wood-frame homes are usually safer, but even those can have brick veneer which will start shaking off if it’s not reinforced. And even for newer homes, “earthquake-safe” doesn’t mean a home is “earthquake-proof.” 

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“You’d be able to exit the building, but you wouldn’t necessarily be able to re-live in it,” McKean said. 

Across the board, those with earthquake expertise recommend earthquake insurance, which doesn’t come standard in homeowner’s insurance policies. It’s hard to know how many Weber County residents have such policies, but calls to agents working in the county found a general consensus — around three to five percent of Weber County homes have earthquake insurance.

Some insurers say it’s the cost. At Farmer’s Insurance in Ogden, for example, earthquake insurance costs the same as regular home insurance premiums. For other policies, the deductible is too high. At American Family Insurance in Ogden, agent JD Parry said the deductible is between 10 and 15 percent of the value of the home.

“That’s not the damage, but what the home is insured for,” he said. “If they have $300,000 home with a 10 percent deductible they pay $30,000 before it even kicks in.”

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That’s a deterrent for a lot of homeowners, but Parry still sees value in a policy. 

“My talking point on that is, a lot of people feel that if something were to happen, FEMA would come in and help. I’ve countered that and said, ‘Have you seen how long it took new Orleans to recover from Katrina?’” he said. “We’re told the big one’s coming. There’s going to be a lot of hurt when it does happen.”

Lance Peterson with Weber County Emergency Management agrees that earthquake safety begins with each household. Along with insurance, he recommends a 72-hour survival kit and a family plan, like where to meet when phone towers and power are out of service.

“The first line of defense is family and individual preparedness, it’s not the federal government, it’s not the state, it’s not the county, it’s not the city,” he said. “People need to be responsible for their own level of preparedness. We’re not the first line of defense.”

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Seismic safety at schools

While an earthquake can cause major damages to Weber County homes, the chances are good it could also strike during the day when no one’s home. That’s why school safety concerns McKean, too. 

“We have a lot of schools that were built before seismic codes, and children are in these schools all day,” he said.

School districts, however, have limited budgets to make seismic upgrades. In 2003, the Weber School District hired a consultant to assess its 12 schools closest to the Wasatch Fault. They found it would cost $21.6 million for needed upgrades. 

“That was in 2003, I’m sure those prices have gone up significantly,” said Chrissy Kotter of Weber School District’s facilities department. 

It’s hard to get the green light on those retrofitting costs, especially when older schools will be replaced at some point anyway. Seven of the schools from the 2003 analysis have since been replaced. The district did determine, though, that any schools or school structures built before 1987 don’t have up-to-date seismic safety standards.

In the Weber School District, 18 elementary schools, three junior high schools and Bonneville, Roy and Weber high schools all need seismic upgrades. The Canyon VIew School, which includes all grade levels, was built in 1968 and also need seismic upgrades.

“Would they still be standing? The original buildings, probably not very well, but the (newer) additions would be,” Kotter said.

For Ogden School District, nine elementary schools, Highland Junior High and Mound Fort Junior High have not recieved seismic upgrades. The two high schools had recent seismic work, although the ROTC building at Ogden High and the gymnasium at Ben Lomond are still not up to code.

Weber County schools and seismic safety status

Zoom to each school and click to see date of construction and seismic safety status. 

Contact Reporter Leia Larsen at 801-625-4289 or llarsen@standard.net. Follow her on Facebook.com/leiainthefield or on Twitter @LeiaLarsen.

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