Is there an explanation for recent rockfalls in Utah?
Jun 2, 2022, 6:40 PM | Updated: 9:17 pm
CEDAR HILLS, Utah — A hiker is in the hospital after a rock the size of a tennis ball hit her on the Timpanogos Cave Trail.
It happened around 7:15 a.m. Thursday, according to Sgt. Spencer Cannon of Utah County Sheriff’s Office. Cannon said the rock knocked the 65-year-old woman unconscious and caused bleeding from her head.
Search and rescue crews carried her off the mountain to a waiting helicopter that flew her to a hospital
This is the third rock fall in Utah in the past few days, the most notable being a massive slide captured at Lake Powell on Memorial Day near the entrance to Warm Creek.
Steve Carter captured the video as the slide sent debris and water shooting into the air.
On June 1, a rockslide closed Mt. Carmel Highway in Zion National Park. After initially clearing the road, the National Park Service staff observed other loose rocks above the road and used a water pump from a fire truck to dislodge them.
A significant rockslide has occurred on Zion Mt Carmel Highway below tunnel. SR-9 is closed from Canyon Junction to East Entrance. No thru traffic
— Zion National Park (@ZionNPS) June 1, 2022
While the incidents were in different parts of the state and were different sizes, they did have one thing in common.
“We did have a big rainfall event over most of the state over Memorial Day weekend so that may be some of what we’re seeing it,” said Rich Giraud, a Senior Geologist with the Utah Geological Survey.
Giraud said rock falls in Utah are sporadic, especially those with injuries. In fact, since 1874 there have been 15 deaths due to rockfalls.
Utah rockfall fatalities since 1850, based on newspaper, reports, and scientific descriptions of events. (Utah Geologic Survey)
“One of the best ways to think about rock fall is they’re very random and they’re very sporadic, but a rock that is on a cliff is continually being conditioned to pop off. Each freeze-thaw, each hot-cold, each rainfall conditions that rock,” he said.
For those who like to recreate in our various Utah landscapes, there are ways to be educated about potential rockfall hazard areas.
Giraud said you can protect yourself by looking for any debris that is already on the ground. “If you’re below a cliff and there is fresh rock on the ground, be aware that a rock fall can happen there and you don’t want to linger or spend too much time there.”
For those who frequent the Lake Powell area, a good resource to keep on hand is the Geological Hazard Report for the high-use areas of Glen Canyon National Monument and Lake Powell. The report lists areas geologists are studying and could be dangerous.
“This is good for people who visit Lake Powell and understanding how to manage your risk on the lake, where you beach your boat, where you camp, where you hike.”
Giraud said the drop in the water level at Lake Powell could also contribute to more rockfalls in the coming years and warned visitors to be cautious. He said pressure in the rock changes with the lack of water.
“When you get the sudden drawdowns, then the changes are more rapid. If it’s slow, it’s not quite as rapid,” he explained.
Geological Hazard Report for the high-use areas of Glen Canyon National Monument and Lake Powell: ss-166.pdf (utah.gov)
