Sequence produces dozens of small earthquakes in southern Utah

This map shows where 53 earthquakes have happened since Nov. 28. All of the small earthquakes have been reported about 12.5 miles southeast of Kanarraville.

This map shows where 53 earthquakes have happened since Nov. 28. All of the small earthquakes have been reported about 12.5 miles southeast of Kanarraville. (University of Utah Seismograph Stations)



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KANARRAVILLE, Iron County — A portion of southern Utah near Zion National Park is still rattling after weeks of small earthquakes, Utah seismologists say.

But other than the fascination of seeing many earthquakes in the same area, there really aren't any concerns of a "big one" ready to hit the area, said Jamie Farrell, a seismologist at the University of Utah Seismograph Stations.

The sequence began in the early morning of Nov. 28. The University of Utah Seismograph Stations recorded a 3.1 magnitude earthquake just east of Kolob Reservoir and about 12.5 miles southeast of Kanarraville.

Only two people reported feeling the initial earthquake, which had a depth of nearly 4 miles, according to Farrell. It didn't cause any damage, but it set off a chain of smaller earthquakes that are still shaking the same area.

The U. station reported Tuesday there have been at least 53 events in the same area over the past month into 2022. That includes a half dozen small earthquakes recorded early Tuesday — the two largest topping out at 2.5 magnitude on the Richter scale.

Fifteen of the earthquakes have been classified at least 2.0 magnitude in strength, while 37 were even weaker than that.

It's unclear how the sequence began. Farrell explains there aren't any mapped fault lines in the area but the series of earthquakes is likely the result of forces underground too small to be mapped.

"These are occurring on some buried fault structure that is too small to have reached the surface, so there's no way to map it at the surface," he said. "(It's) just some small fraction system that's probably rupturing down there."

This, he adds, is common for most earthquakes reported in Utah. They don't occur by large faults like many along the Wasatch Front.

Sequences like what's happening in southern Utah can go on for months, which is why more earthquakes will likely be reported southeast of Kanarraville in the near future. But there are no indications it's a foreshock, or a minor earthquake leading to something bigger.

There was also a 3.6 magnitude earthquake centered about 5 miles east of Zion National Park last month, which is the largest quake in that specific area in over 60 years. University seismologists said that was an unrelated event from the sequence located closer to Kanarraville.

Contributing: Eliza Pace

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