Another Landslide Rocks Mount Adams; No Link Seen Measures 1,500 Feet Thick And 750 Feet Wide

For the second time in seven weeks, a massive landslide has occurred on Mount Adams, this time on the southeastern slope of the 12,276-foot volcano.

Scientists said the slide began at 12:30 a.m. Monday at about 11,200 feet elevation and roared more than three miles down Klickitat Glacier, stopping at 5,200 feet on Big Muddy Creek.

That side of the mountain, the third highest in the Cascade Range and second highest in Washington state, is part of the Yakama Indian Reservation. It is about 75 miles northeast of Portland, Ore.

No injury to people or damage to structures was reported, and no one has been reported missing, authorities said.

The slide was 1,500 feet thick and 750 feet wide at its source on Battlement Ridge, just below a formation known as the Castle, said Richard Iverson, a scientist from the U.S. Geological Survey’s Cascade Volcano Observatory in Vancouver after a flight over Mount Adams on Tuesday.

He said the landslide might be even larger than one down the southwest face on Aug. 30, the largest slide on the hump-like, snowcapped peak since 1921.

Both apparently were triggered by heavy rain.

“It’s roughly the same size as the one that occurred seven weeks ago,” said Iverson, who works for the U.S. Geological Survey. “This slide is largely rock debris, while the other was predominantly snow and ice.

“Like the previous slide, there was no conspicuous geological trigger, such as an earthquake or volcanic action. There may be a meteorological link because we’ve had exceptionally wet weather the last couple of years.”

Iverson estimated the volume at 2 to 3 million cubic meters of rock.

“It’s really intriguing that two large slides occurred in roughly a seven-week period,” he added. “There is no clear connection between them, but they provoke further thinking about the issue.”

Unlike the previous slide, this one was recorded as it happened on earthquake monitoring equipment.

Darryl Lloyd, of Glenwood, said he noticed the slide when he woke up Monday morning and immediately chartered an airplane to take aerial photographs.

“It’s quite an imposing sight,” Lloyd said. “The upper part of the mountain now has a thousand-foot cliff with parts that overhang. The lower part of the slide is at least a half-mile wide.”