New Mapping Of The Wasatch Fault Published Online

May 1, 2020

Along the Wasatch Front many people live and work near and on scarps of the Wasatch and West Valley fault zones. Using high-resolution elevation data (lidar), UGS geologists mapped fault traces (bar and ball on downthrown side of fault) and defined special study zones along the Wasatch Front. Compared to previous mapping, geologists located more surface fault traces giving us a better idea of how to live in earthquake country.
Credit Utah Geological Survey

While the recent Magna earthquake may have taken many Utahns by surprise, geologists at the Utah Geological Survey were hard at work finishing a four-year, fault-mapping study they hope will help reduce earthquake risks in the state. 

“This was actually the first time we've published a mapping just online. The idea is that people will be able to interact with the data more easily. So this way they can actually explore and look at the fault mapping and, you know, show where it is in relation to the house," said Emily Kleber, a Hazards Geologist with the Utah Geological Survey.

The new mapping Kleber is talking about is being done in collaboration with the U.S. Geological Survey and uses high-resolution elevation surveys (lidar), previous mapping, studies of ancient earthquakes and field mapping to map new fault traces and increase the detail on existing fault traces.

The study also identifies “special study zones” around the fault traces where ground deformation can occur.

“These are meant to be sort of red flag, kind of awareness zones for local municipalities, maybe eventually state but we're non-regulatory,” said Kleber. “So these are just sort of our best way to help communicate the surface fault rupture hazard, and encourage the need to develop ordinances around building around and on top of fault zones.”

Faults in the Wasatch Front are capable of generating earthquakes approximately up to magnitude 7.6, releasing about 700 times more energy than the Magna earthquake. At magnitude 6.5 an earthquake can rupture the ground surface producing a fault scarp, uplift, of several inches to up to 20 feet high, extending for up to 40 miles. On the valley or “downthrown” side of the fault, the ground can crack, tilt and fault as well.

Kleber said the UGS is actively working to make data on geologic hazards more accessible to the public, including local governments, developers and individual homeowners. She also said they are working on a hazards app to make access even easier.

“People still have to determine what their individual risk is, we can't determine what their risk is. So the message we try and give people is, you know, we help you understand the hazards, but you have to figure out what your risk is," Kleber said. 

The Report of Investigations 280 can be accessed here.

Public access for the new mapping can be accessed here.