SALT LAKE CITY — Several rockfalls across Utah in recent weeks are putting renewed attention on a geological hazard that experts say can happen with little to no warning.
Provo Canyon, Zion and Parleys Canyon have all experienced recent rockfalls. On Sunday night, rock debris in Parleys Canyon forced the closure of part of I-215.
Greg McDonald, a senior hazards geologist with the Utah Geological Survey, said experts can identify areas where there is potential for rockfall, but predicting exactly when one will happen is much more difficult.
“For something to trigger rockfall, they can be triggered by earthquakes, or weather,” McDonald said. “I think the one we saw yesterday was likely just due to the prolonged weekend rain.”
However, a rockfall can be years in the making.
“The source of the rockfall is usually conditioned over years by freeze, thaw, and weathering processes,” McDonald said.
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The Utah Geological Survey studies rockfalls along with landslides, debris flows and other geological hazards. McDonald said the agency is currently working on hazard mapping along the Wasatch Front.
“We’ve done a bunch of hazard maps down in the St. George area,” McDonald said. “We focus on areas with rapid growth basically to try to get ahead of some of the development so they can be developed responsibly and deal with hazards before they occur.”
While recent rockfalls such as the one in Parleys Canyon are not necessarily surprising to geologists, McDonald said they can be extremely dangerous because of how suddenly they occur.
“They usually just occur with no warning,” he said. “It’s one of those things. It’s just a bad moment when they occur.”
For people out hiking like Emilio Cantu, the possibility of encountering a rockslide isn't necessarily something he’s used to.
“A rockslide never crossed my mind,” Cantu said.
Recent rain can make Utah’s canyons especially scenic, but the recent rockfalls serve as a reminder to stay aware of your surroundings when driving or hiking in areas surrounded by cliffs and boulders.