ALASKA—In spring 2020, scientists identified a large, steep, potentially unstable slope on the Chugach National Forest in the Barry Arm fjord, located 30 miles northeast of Whittier, Alaska. A landslide at this site could fall into seawater, generating a tsunami that would have devastating effects on those who live, work and recreate in and around Whittier and northern Prince William Sound.

Throughout 2020, the Forest Service participated in a state and federal agency team, working together to monitor, assess and collect baseline data, inform Prince William Sound communities and users, and to develop early detection warning systems. Scientists monitored motion by comparing data on the site collected at different times using a variety of scientific techniques including satellite-based radar, airborne lidar (a kind of radar that uses light pulses), and aerial photograph-based mapping. Seismometers and a remote camera have been installed on Chugach National Forest-managed lands. And the National Tsunami Warning Center plans to install tsunami gauges in the Barry Arm and Port Wells region this spring to monitor for a tsunami should a landslide occur. These gauges would indicate any unusual volume of water level change in a short amount of time.

“The risk of landslide-induced tsunami's in Prince William Sound and Southeast Alaska is not new,” said National Tsunami Warning Center Tsunami Warning Coordinator Dave Snider. “Our challenge is knowing that they occur and helping keep people and property out of harm's way. Being aware of the risk and having a tsunami safety plan when enjoying our state's wild areas is always a smart move.”

Throughout 2020, Forest Service staff worked with the National Tsunami Warning Center, Alaska Department of Homeland Security and Management, Alaska Division of Geological and Geophysical Surveys, Alaska Earthquake Center, United States Geological Survey, and National Oceanic and Atmospheric Administration to facilitate and permit sensor installations and survey work. The Forest Service also provided review and a letter of support for a National Science Foundation Coastlines and People grant. That request proposed assessing the emerging hazards of landslides and landslide-generated tsunamis in coastal landscapes in Alaska due to alpine permafrost thaws and glacial thinning caused by climate change.

“Each of these cooperating agencies has unique expertise, resources and jurisdiction for a slide of this potential impact,” said Glacier District Ranger and landslide team representative Tim Charnon. “We’ve been glad we can help facilitate this assessment through special use permits, logistical support and communication with the public, our special use permit holders, Prince William Sound communities and our tribal partners.”

Scientists continue meeting routinely to discuss their observations, share information about any notable changes, and work with emergency management agencies. The newest information and updates, including interagency-coordinated press releases, email alerts and social media posts, can be found at the official site for the Barry Arm Landslide.