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Trench could help Utah better prepare for earthquakes

Posted at 4:50 PM, Aug 03, 2022
and last updated 2022-08-03 20:07:13-04

SALT LAKE CITY — Scientists have dug a pair of trenches in a field near I-215, giving them a rare look at the West Valley fault line.

It's a cross section of the fault line, which is like a branch of the much larger Wasatch Fault. They're studying the soil layers to gain new insight into the West Valley fault, which can help inform them about earthquake cycles and seismic activity in the area.

"It's really important for our study that our soil be preserved. From the very top, the stuff we walk on, on down. No asphalt, no digging, no excavation, anything like that," said Emily Kleber, a geologist with the Utah Geological Survey.

It's one of the few places left in the Salt Lake Valley they can do this type of field research. Increasing urbanization has limited where geologists can dig.

"It’s one of the few spots left out here that’s been untouched by human hands, or should I say bulldozers," Utah State Geologist Bill Keach said.

Geologist Adam Hiscock showed FOX 13 News the trench, pointing out layers of soil that date back to prehistoric Lake Bonneville. He pointed out the fault line, where the rock demonstrates some upheaval.

"To generate a rupture that goes all the way to the surface, you need at least a magnitude 6.5," he said. "The Magna earthquake was a 5.7. So it was too small of an earthquake to generate a rupture all the way to the ground surface and see evidence. So this would have been at least a 6.5."

The research being conducted in the field has real-world impacts. It can help communities do things like upgrade building codes in the area and take steps to ensure people are prepared for the next earthquake.

"It has huge implications for us in the valley," Kleber said.

The Utah Geological Survey will finish their work on the trenches and fill them back in. They have photographed it extensively, marking data points on prints. Soil samples collected will be sent off for analysis. The results of the research could be published within the next year.

"Sound science leads to sound policy," said Keach. "If we can get people to be aware and to prepare, then they don’t have anything to be afraid of."