Scientists have discovered evidence of four big earthquakes that rocked the Salt Lake Valley long before pioneers arrived — and they’re not on the well-known Wasatch Fault on the East Bench.
Geologists are getting their first good look at the West Valley Fault zone, just west of the Salt Lake International Airport. They’ve wanted to dig trenches in the area for years.
“We suspected that there had been numerous earthquakes in this region,” said Chris DuRoss of the Utah Geological Survey.
The West Valley Fault zone is actually comprised of a dozen different fractures. They lie roughly between Redwood Road and 5600 West from about 1700 North to 4800 South. But since at least the 1980s the area on the margins of the Great Salt Lake has been too soggy to dig.
Over the last decade the shrinking lake receded several miles from the fault zone, and the water table has dropped. Now that the Utah Geological Survey has been able to dig three trenches, the water table is visible 10 feet below the surface.
Recently geologists had their first look underground, and it confirms their suspicions. The horizontal layers of sediment show clear signs of being broken by fault movements. It’s clear evidence of four big earthquakes in the last 15,000 years.