After a day of aerial and ground searches Monday, Colorado officials failed to find three men who vanished after a massive weekend mudslide wiped out miles of uninhabited land on Grand Mesa, the largest flat-topped mountain in the world. (See footage of the devastation below.)
The disaster began Sunday morning, officials say, when a small mudslide cut off irrigation water for farmers near the West Salt Creek in Mesa County, in western Colorado.
Wes Hawkins, 46, Clancy Nichols, 53, and his son, Danny Nichols, 24, went to the area to investigate the water stoppage. They were apparently there when a second, massive mudslide broke loose, sweeping down the foothills with a roar.
The men have not been heard from since, nor have rescuers been able to find the vehicle and the ATV that officials said they took with them.
They may be trapped in the vast, unstable swath of mud, stone and shattered pine trees that covers up to 8 square miles of private land. Some areas are thought to be buried beneath as much as 250 feet of debris.
The immense power and scope of the slide -- which, according to rough estimates, could be as much as eight times larger than the landslide that killed at least 41 people in Snohomish County, Wash., in March -- astonished Colorado officials who surveyed the area by air on Monday.
“The slide came down with so much force and velocity that it came to a hill and came up and over a hill and came back down -- a significant hill," Mesa County Sheriff Stan Hilkey told reporters.
A "sheer wall" remains where the mountain broke away on U.S. Forest Service property, and further slides are possible, warned the sheriff, who blamed recent rains for the slide.
National Weather Service meteorologist Tom Renwick said the area had received 0.3 to 0.7 inches of rain Saturday and 0.4 to 0.5 inches of rain Sunday -- somewhat normal totals for storms in the area.
"When you add them up, that’s not really impressive," Renwick said of the rainfall, at most totaling 1.2 inches over two days. But the closest sensor was nine miles from the slide, he said, so the affected area might have been hit harder.
The upper two-thirds of the slide remained unstable and dangerous on Monday, officials said. Drones with infrared cameras and 40 to 50 rescuers on foot scoured the edges of the devastated area to the extent that it was safe to do so, halting as daylight faded.
“We don’t want to create any more of a tragedy than this already is," Hilkey said, adding of the missing men, “We hope they may be stranded somewhere in such a way that they’ve avoided it."
No structures have been reported lost and no evacuations have been necessary. Officials said several gas wells in the area had been shut down as a precaution.
Kate Porras, a spokeswoman for the Mesa County Joint Information Center, said the slide had moved about 20 feet overnight and "was still shifting out" on Monday. "It still was pretty unstable,” she said.
Officials estimated the size of the Grand Mesa slide at up to 4 miles wide and 2 miles long -- about 8 square miles. The landslide that wiped out a subdivision in Snohomish County, Wash., destroyed about 1 square mile of land.
When asked how long cleanup might take, Hilkey, the sheriff, said, "I don’t think that the cleanup will occur. We have to assess how much we can do."
He added, “This one we’re measuring in miles, and half-mile increments, and the depth of it is overwhelming."
Hilkey said he had spoken with officials in the Snohomish County Sheriff's Office in Washington on Monday morning and gotten advice on how to handle the initial stages of the slide search.
An update on the search effort was expected at a news conference Tuesday morning.