MILLARD COUNTY, Utah (ABC4) – If you’ve driven through central Utah on I-15 near Fillmore, you may have noticed some smooth hills and fields of black rock. 

The area is named the Black Rock Desert. It may not look like much, but you’re looking at some of Utah’s volcanoes.

The Black Rock Desert is the youngest volcanic field in Utah, the Utah Geological Survey shares. There are no current signs of eruptions. However, the volcanoes are still active, and a recent discovery about earthquake generated waveforms have left scientists wanting to know more.

Courtesy: University of Utah

According to a study shared by the University of Utah, a pair of earthquake sequences in September 2018 and April 2019 focused scientists’ attention on the Black Rock Desert in Central Utah. 

Scientists say the sequences, which included the main quakes and their aftershocks, were very different from the Magna earthquake that shook the Wasatch Front on March 18, 2020 and other Utah earthquakes. 

Pankow, Ph.D. Research Professor of Geophysics & Assoc. Director of Seismograph Stations for the University of Utah contributed to the study. She tells ABC4 the Magna earthquake occurred on the Wasatch Fault in the Salt Lake Valley, as the result of stretching in the crust. 

The Black Rock earthquakes, located within the footprint of the Black Rock volcanic field near Fillmore, is around 150 miles to the south of the Magna earthquake location. “The results of this study suggest that these earthquakes are the result of processes within the volcanic field,” Pankow shares. 

According to the Utah Geological Survey, the Black Rock Desert is a volcanic area, or volcanic field, covering more than 700 square miles in eastern Millard County. 

Officials explain episodic volcanic activity occurred at the Black Rock Desert a couple of million years ago up to a few centuries ago, leaving intriguing landforms and features including volcanic cones, lava tubes, pressure ridges, and craters. 

“The Black Rock Desert lies within the Basin and Range physiographic province, which has been shaped over the past 17 million years by stretching and uplift of the Earth’s crust. Extension resulted in development of faults in the thinning crust, creating a recurrent pattern of linear north-south trending mountain ranges and valleys. Some of the faults have been conduits for magma (and water) to reach the surface; many of the volcanic cones, vents, and hot springs in the Black Rock Desert align with the faults. Currently, the Black Rock Desert may be the largest geothermal prospect in Utah,” as stated on the Utah Geological Survey’s website. 

The Black Rock sequences were captured by the Utah Regional Seismic Network and by nearby temporary seismic equipment deployment that was monitoring a geothermal well, the study shares. 

“Earthquakes in the Black Rock Desert are rare, and capturing the seismic recordings from these earthquakes provides a glimpse into the volcanic system of the Black Rock Desert that, while not showing any signs of erupting, is still active,” as stated in the study. 

Pankow tells ABC4 “the University of Utah Seismograph Stations monitors all seismic activity in the State of Utah.”

She says these earthquakes located in the Black Rock Desert were large enough to alarm the duty seismologist. “In responding to the alarms, these earthquakes were determined to be unusual: The earthquakes located in an area where we do not typically detect earthquakes and the earthquakes generated unusual waveform characteristics compared to more typical Utah earthquakes,” Pankow shares. 

Courtesy: Utah Geological Survey

Central Utah is not the only area of the state with volcanos, Pankow tells ABC4. She says some examples are the Marysvale volcanic center and adds there are also volcanic deposits at Snow Canyon State Park.  

Pankow says this is her first study related to volcanoes in Utah. She says the University of Utah being able to study seismic signals related to Utah volcanos, to associate the signals as having a volcanic-like origin is “a very exciting discovery.”

To the untrained eye, it’s hard to know if you are near, or even on a volcano. You could have been right near one and had no idea what it was. Pankow says “one clear sign of a volcano is the rocks on the surface. For instance, in the Black Rock Desert, one of the primary rocks is Basalt. These are rocks that would have occurred from a volcanic eruption around 10,000 years ago. Other features are cone-shaped volcanic rocks.”   

According to the results of the study, scientists should give more attention to the Black Rock area and look into improveing seismic and volcanic monitoring in this area so that Utah’s population is aware of small changes that may occur.