ST. GEORGE — Eric Clapton once sang about shaking his tambourine “after midnight,” and that song may have been appropriate for local residents who reported shaking just after midnight Friday.
Update Dec. 1, 11 a.m. Additional information including foreshock possibilities, shallowness of quake and location away from Hurricane Fault.
A 3.9 magnitude earthquake centered in Kolob Canyon occurred at 12:16 a.m. early Friday and was followed by a 2.6 magnitude aftershock near the same area at 1:27 a.m. The center of the earthquakes was located about 10 miles east of New Harmony, 7 miles south-southeast of Kanarraville and 17 miles south of Cedar City.
On social media, people in Cedar City, Hurricane and the Red Cliffs area of St. George reported feeling the tremor describing it as “loud” and “needing to hold things down.” According to the U.S. Geological Survey, an earthquake between 2.5 and 5.0 is capable of being felt but not likely to cause any more than minor damage.
The University of Utah Seismograph Stations said in a statement that the earthquake would have been widely felt in the areas of Cedar City and Hurricane.
“A total of 21 earthquakes of magnitude 3.0 or greater have occurred within 16 miles of the epicenter of this event since 1962,” the statement said.
Jamie Farrell, a research associate professor with the University of Utah Seismograph Stations, told St. George News there is a slim chance Friday’s earthquake is a foreshock to something bigger.
“There is about a 5% chance that an event is a foreshock to an upcoming larger event,” Farrell said. However, that chance decreases with increasing time after the event.”
After it was initially thought that the earthquake and aftershock Friday occurred on the Hurricane Fault, which runs from Cedar City to Northern Arizona and forms the Hurricane Cliffs.
“As this event is located 9.5 kilometers east of the Hurricane Fault and the Hurricane Fault dips to the west with depth, it is unlikely that this event occurred on the Hurricane Fault,” Farrell said.
The Hurricane Fault fault caused the strongest earthquake locally in recent history – the Sept. 2, 1992 5.7-magnitude earthquake centered in Washington City, which triggered a landslide in Springdale that destroyed three houses and temporarily closed the entrance to Zion National Park.
Fire departments and law enforcement throughout the area had no reports of damage or call-ins from Friday’s earthquake.
“We didn’t receive any calls,” officer Dan Raddatz with the Hurricane Police Department told St. George News. “I noticed a couple of Facebook posts in local Hurricane groups mentioning houses rattling. But nothing came directly to the PD.”
Chief Mike Phillips with the Cedar City Fire Department also reported to St. George News that they received no calls to their department, as did a dispatcher with the St. George Police Department.
Friday’s earthquakes were also extremely shallow according to Farrell, making it more intense that a deeper tremor of the same magnitude would be. Both quakes were within eight miles of depth.
“The shallower an event is, the larger amplitude shaking would be experienced on the surface for the simple fact that you are closer to the hypocenter,” he said. “In general, the amplitude of the shaking decreases with distance from the hypocenter.”
Earlier this week, on Tuesday, an unrelated 2.9-magnitude earthquake on the Toroweep Fault occurred near Hildale.
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