Landslides happen all the time in Alaska. But historically, the main way experts found out about a landslide was if someone witnessed it themselves.
“Like someone flying by, or someone would just see something in the remote sensing imagery,” said Ezgi Karasozen, a research seismologist with the Alaska Earthquake Center.
She said that’s posed a real challenge to cataloging landslides and learning more about them. In some cases, a slide could go unnoticed and unrecorded for months – if not longer.
That could soon change. The center has a sprawling network of seismic stations across the state that are primarily used to detect earthquakes. Several years ago, Karasozen and a colleague set out to see if they could be used for landslides, too.
“It turns out, we can do that,” Karasozen said.
The effort involved creating an algorithm capable of recognizing the specific seismic signals usually associated with slides, which are quite different from those associated with earthquakes. Today, some 200 stations across Alaska use that algorithm. It’s a work in progress, but is designed to detect slides, pinpoint where they happened and even estimate their size.
“We’re continuously improving this algorithm to make it more robust,” Karsozen said.
Now the network stands to fill a major knowledge gap amid heightened concern about landslides and their potential impacts on communities, infrastructure and mariners.
Just last year, a gargantuan slide in the Tracy Arm fjord near Juneau generated one of the tallest tsunamis on record. Nobody died, but experts say the wave could have overturned boats – including cruise ships – had any been present.
That and other recent tsunamis have spurred a more urgent conversation around the need for more landslide monitoring and warning systems. As Karasozen sees it, the seismic network could contribute to that goal.
“Obviously we are doing this for the hazard itself,” she said. “So in one shape or form, hopefully there will be a warning system at some point.”
A complicating factor is that Alaska is incredibly seismically active. That means the Earthquake Center’s stations are constantly picking up signals from earthquakes, but also glaciers calving, rock fall and more. So the big challenge is filtering out landslide signals from all the others – and preventing false detections.
“It’s fair to say that this research is still quite young and we’re still in the developing phase,” she said.
It could be years before the algorithm is reliable enough to feed into a reliable early warning system.
“Even with earthquakes, we have like 50 years of monitoring everything going on, even more, and we are still developing an earthquake early warning system even now,” Karasozen said.
