Nearly everyone living on Utah’s Wasatch Front relies on water delivered via three major aqueducts built in the 1950s, an era when little attention was paid to seismic risks. These lines cross a major fault that is expected to unleash a strong earthquake in the coming years, leaving Utahns vulnerable to prolonged disruption in water service and other utilities, according to speakers at a major seismic safety conference Tuesday in Salt Lake City.
“Because it was conveniently flat right where the fault line was, [the aqueducts] actually follow and cross the fault line in a number of places. They could not be in a worse position for the future of Utah,” said Robert Grow, the founder of Envision Utah, while participating in a panel discussion. “It’s unlikely that a large earthquake would leave those three aqueducts intact.”
In addition to collapsed roadways, power disruptions and crumbling brick buildings, a large quake would cause more than a million Utahns to be without water for months. He said the state needs to put up at least $192 million to fund aqueduct upgrades.
“Without them, we will not get back into operating position in Utah for a long time [following a major quake.] We know that at the time of the earthquake, about 1.5 million people would be without water. Even 90 days later, it’s still over a million people,” he said. “By then, many people will have voted with their feet and have left. And the Utah economy will probably be permanently damaged in ways that we may never recover.”
Two years ago, the 5.7 magnitude Magna earthquake gave residents a small taste of what’s in store for Utah.
There is a 57% probability that the Wasatch Front region will experience at least one magnitude 6.0 or greater earthquake in the next 50 years and a 43% probability of at least one magnitude 6.75 or greater earthquake in that period, according to the Utah Geological Survey.
Were a quake of that size to occur now, it would result in $33 billion in property damage and claim up to 2,500 lives, according to a 2015 report by the Utah Seismic Safety Commission.
The weeklong 12th National Conference on Earthquake Engineering is hosted by the Earthquake Engineering Research Institute, or EERI, at the Salt Palace with help from Envision Utah.
Delivering the conference’s keynote, Gov. Spencer Cox emphasized the need for collaboration and aggressive planning to upgrade homes and infrastructure to ensure they withstand the worst effects of a major quake.
He said Utah has proven itself adept at responding to disasters but it has not been as good at preparing for them.
“We need to do better educating the public about the dangers of unreinforced masonry, which of course, increases the pressure to upgrade buildings,” Cox said, ticking off the first of five recommendations put forward by the Seismic Safety Commission. Hundreds of older brick homes, a hallmark of Utah’s historic neighborhoods, are at risk of collapse in a big quake. Retrofitting these buildings would cost $253 million.
Utah’s most iconic building, the Salt Lake Temple, a Gothic-style church built of granite blocks in 1893, is undergoing a retrofit. Its state-of-the-art base-isolation system will allow it to move 5 feet in any direction if the ground shakes, Cox noted.
Other crucial steps the governor highlighted included retrofitting or replacing seismically unsound schools and developing an early-warning system.
“All of this takes funding and commitment,” Cox said. “It’s important for all of us to be involved. The entire community needs to address and mitigate earthquake risk.”
The insured value of the Utah schools that should be replaced exceeds $2 billion, according to Jessica Chappell, a structural engineer who serves as the vice chair of the Utah Seismic Safety Commission.
“We know that the cost of replacement is significantly higher than their insured value,” Chappell said. “Our school systems are both a success story and still a major problem. We have, since the 1980s, dramatically reduced our stock of unreinforced masonry schools.”
The 2020 quake, which damaged 77 historic buildings, drove home the vulnerability of brick buildings to ground shaking. While no serious injuries were reported, Magna’s historic downtown took a beating, with brick facades and parapets tumbling onto the sidewalks.
“One of the biggest factors that impacts the state of Utah is that we did not have a statewide building code adoption until 1975,” Chappell said, “so it was legal to permit unreinforced masonry structures up to that point.”
According to Rep. V. Lowry Snow, R-Santa Clara, Utah’s path forward will need stronger political leadership than has been previously demonstrated regarding seismic preparedness.
“You have to have leaders that are willing to engage in developing foresight, willing to look into the future and get beyond whatever it is that’s immediately on their plate,” Snow said, “and say, ‘What are some of the long-term issues that are affecting those who elected me to protect them and to manage well the assets that have been entrusted to me.’”
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