Scientists intrigued by 2 Southeast Alaska landslides in 1 week

Published: Sep. 20, 2022 at 3:55 PM AKDT
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ANCHORAGE, Alaska (KTUU) - Two large landslides in Alaska have let loose in the last week, and although neither impacted residents, they are of great interest to geologists.

The first slide was east of Seward, detected on Sept. 14 as it fell onto Ellsworth Glacier. Geologist Bretwood “Hig” Higman said debris from that slide is estimated to be about 10 million tons in volume.

“That would be about 100 times the volume of the landslide that happened on Lowell Point Road [near Seward] earlier this year,” Higman said.

He said landslides like this only happen in Alaska about once a year.

“There’s a steep mountainside there, that kind of the whole side of the ridge came down, hit the glacier and spread out across the glacier. It went all the way across to the other side of the glacier. It was a dramatic enough failure that it actually created seismic waves that are really distinctive of landslides,” Higman said.

It was the seismic monitoring data that initially alerted scientists to the slide. It was not found by someone in Alaska, but instead by a professor of Earth and environmental sciences at Columbia University in New York.

“It’s almost 20 years ago now I wrote some code to look for signals of earthquakes that don’t start with a sharp jolt,” professor Goran Ekstrom said.

Today Ekstrom’s code programs a complex system of sensors that monitors seismic activity.

Most earthquakes start with a sharp jolt which is measurable as a p-wave.

Normally the system gets about 10 pings a day, each one representing some kind of seismic activity. Ekstrom has to manually analyze the data to see if they are actually landslides.

The second landslide fell Saturday onto Lamplugh Glacier in southeast Alaska. Scientists initially thought it could have been at the same spot as a 2016 landslide, which was even bigger.

“It turns out, it’s actually separated. It’s not very far away. And the 2016 landslide came down one direction and went way down the glacier. This one came and actually crossed it, it was going a different direction,” Higman said.

Thankfully, the human impact of this slide was minimal.

“It’s a remote glacier. Obviously, in some cases, you might imagine there’d be someone up there skiing on the glacier or whatever,” he said. “So there is some hazard posed by these. But mostly, if you have a case like this, where it’s on a remote glacier, that’s where you want these things to be happening.”

Higman said while these landslides didn’t affect people, scientists will be studying them to see what they can learn about what might happen with other dangerous landslides.

He said while scientists cannot yet prove what caused the slides, they could be related to the recent rainy weather and the impact of retreating glaciers.