Michelle Tessier, Deseret News
NORTH SALT LAKE — Ten days after a massive landslide destroyed a home, damaged a tennis club and temporarily forced the evacuation of more than two dozen homes, families remain on edge each time another storm threatens.
But since that initial slide, sensors that geologists placed on the hillside have detected no further movement.
"They essentially have told us that the landslide itself does not appear to be moving," Gregg Beukelman, a geologist with the Utah Geological Survey, said of the sensors that are checked twice a week.
He and another state geologist walked around the entire massive gouge in the earth a few hours after it happened and took photos. Their first impression that day?
"Oh my, that's a lot bigger than we had any idea it was going to be," Beukelman said.
They're still trying to assess whether the earth will keep moving. The U.S. Geological Survey calculated that the slide, 60 feet high and about 500 feet wide, contained about 300,000 cubic yards of material and covered an area of 250,000 square feet — about twice the size of the EnergySolutions Arena.
The lack of movement since the slide surprises Beukelman. Usually there's at least minor movement, he said, or shaking out right after the slide.
"It appears as though this slide moved, came to a stop, and so far, that's as far as it's gone," he said today from the toe of the slide at the Eagleridge Tennis and Swim Club.
The geologist said he was also surprised that morning that despite a drenching thunderstorm the night before, the debris was not muddy.
"Most landslides have water pouring out of the toe, pouring out of various spots on the landslide," he said.
Crews usually have to wear waders when they survey a landslide. But not here. He said that tells him something about the role of the storm.
"Was it the major factor? Probably not," he said. "But, it was a contributing factor."
This week, the Utah Geological Survey published all of the pictures and documents related to the landslide online. Beukelman said the pictures and documents help clarify what happened, but not necessarily why the earth slid when it did.
Among the materials online, video of a deep crevice a resident shot six days before the slide.
"That was a big feature," said Beukelman.
That's an indication that the slope "started to move prior to last Tuesday," he said.
There were no telltale signs of the magnitude or depth of the slide to come. But that day, North Salt Lake sent a letter to nearby residents alerting them that the hillside above their homes had started to move:
"There are crevices along the slope which continue to grow larger and there is now a slow moving landside," the letter read. "As a precaution you may want to move any valuables on the basement floor to a safer place in case there is a heavy thunderstorm."
The city drilled holes to try to find out more. Six days later, the debris was unstoppable.
"There are a lot of slopes like this, and a lot of developments like this, and it's unique that this landslide occurred," the geologist said.
North Salt Lake is still working to stabilize the slope, find out why it slid, and trying to determine whether any more movement is imminent.
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