- 2:40 p.m. – NDOT statement on Nevada bridges added
- 2:54 p.m. – Aftershock added to listing
- 3:09 p.m. – People reflect – added
- 3:30 p.m. – Latest estimate of magnitude by University of Nevada, Reno, added
- 4 p.m. – Arizona Department of Public Safety – report from the Gorge
- 4:15 p.m. – Additional closures made by NDOT
ST. GEORGE — An earthquake 39 kilometers south-southwest of Caliente, Nevada, and 63 miles west-southwest of St. George, was felt in Southern Utah Friday.
Although no immediate damage was reported in St. George, or in Mesquite or Caliente, Nevada, possible structural damage has been reported by Nevada Department of Transportation, resulting in U.S. 95 ramps to Interstate 15 southbound and northbound being closed, well as the MLK on onramp to I-15 southbound. Motorists are advised to use alternate routes.
Shannon Miller, dispatcher for the Sheriff’s Office in Caliente, Nevada, said, “We have not had any reports of damage. Mostly everyone was just startled by it.”
Magnitude and aftershocks
Initial reports measured the primary earthquake at magnitude 5.4, but analysts later placed the main quake at magnitude 4.8, University of Utah Seismologist Katherine Whidden said at about 1:30 p.m. MDT. On the other hand, Mickey Cassar, seismologist with the Seismological Laboratory, University of Nevada in Reno said the latest estimate, at about 3:15 p.m. MDT, they are making is 5.28 magnitude.
The main quake occurred at 11:47 PDT, 12:47 p.m. MDT, followed by a series of aftershocks. University of Utah seismograph stations website lists the following, among others of lower magnitude:
- a magnitude 3.8 earthquake within a mile of the first one at 12:05 p.m. PST, 1:05 p.m MDT
- a magnitude 3.0 earthquake within 2 miles of the first event at 12:19 p.m. PST, 1:13 p.m. MDT
- a magnitude 3.4 earthquake within 1 mile of the first event at 12:41 p.m. PST, 1:41 p.m. MDT
Additional aftershocks may be expected.
In the seismology graph below, the main quake can be seen in the color green, with the greater of the aftershocks shown in red, black and blue.
The initial quake was felt across southern Nevada, in Las Vegas and Mesquite, as well as in Southern Utah, from St. George to Cedar City, and Hildale.
As of 3:15 p.m. PDT, 4:15 p.m. MDT, Nevada Department of Transportation has posted an alert advising that ramps from U.S. 95 to I-15 northbound and southbound are both closed, as well as the MLK on onramp to I-15 southbound.
With regard to its closures, Nevada Department of Transportation posted the following statement:
NDOT inspects its 1,100 bridges statewide at least twice a year. All of our bridge structures are designed to withstand rigorous wind and earthquake loading. Nevada lies within an active seismic zone, which is something that we take into account during the project design and engineering phase. Nevada consequently has some of the best rated bridges in the country, according to a recent report by the American Road and Transportation Builders Association (ARTBA). Only 1.8 percent of Nevada bridges are classified as structurally deficient, which is the lowest in the country.
There were no apparent impacts on Interstate 15 through the Virgin River Gorge and no rockslides, Arizona Department of Public Safety Highway Patrol Sgt. John Bottoms said. He had been sitting on the side of the road when the earthquake occurred, he said, and felt nothing.
Mesquite, Nevada, resident Denise Vaughn said he had never felt an earthquake before and wasn’t sure what was happening.
“I kept looking at the clock and realized this was going on longer than just a little shake,” Vaughn said. “Chains on the ceiling fans were moving all over and the bed was shaking. I stood up and thought to myself … I can now say I have ‘felt the earth move under my feet.'”
Great Basin Foods employee Logan Decker, in Caliente, Nevada, said, “It wasn’t bad. We had some small stuff fall of the shelves. But it wasn’t too bad.”
- University of Utah Seismograph Stations informative booklet, provided here: Putting Down Roots in Earthquake Country.
- University of Utah Seismograph Stations
- Utah Geological Survey