Last fall, scientists from the U.S. Geological Survey, Alaska Division of Geological & Geophysical Surveys, Alaska Earthquake Center, and National Tsunami Warning Center were busy preparing weather stations, cameras, seismometers, a ground-based radar system, and water level sensors in Barry Arm for the harsh Alaska winter. Deep snow can bury instruments and solar panels, makes it difficult to access (and even find) sites, and can shift throughout winter and during spring melt. We have made our best effort to harden the sensors, power systems, and telemetry for the equipment to survive. However, it is necessary to have reasonable expectations given the difficulties of working in this harsh environment. Reasonable expectations include:
Regardless, scientists at the U.S. Geological Survey, the Alaska Division of Geological & Geophysical Surveys, and the National Tsunami Warning Center will continue to monitor the landslide movement and provide further details on Friday, February 3, unless significant changes warrant earlier updates.
USGS employees board the Voyager operated by Lazy Otter Charters during 2022 fieldwork
Malcolm Herstand with DGGS works on the Mt. Doran repeater site
Scott Langly with NTWC upgrading the power system at the North Shore water level sensor as part of the 2022 winterization effort
Pathfinder pilot Andrew Chan flying past Cascade Glacier after a day of fieldwork
USGS researcher Dennis Staley looking over Barry Fjord from the Mt. Doran repeater site
(Last updated November 10, 2022)
On August 26, 2022, we reported that a ground-based synthetic aperture radar instrument installed on the east side of Barry Arm revealed the movement of a portion of the Barry Arm landslide (known as the Kite) beginning early in the morning on August 21, 2022. The movement spread from the Kite to other parts of the landslide beginning on August 28. The rate and location of motion were confirmed using satellite imagery on September 13.
Radar data show that the landslide began slowing on October 13, with widespread cessation of movement on October 31. Recent analysis has revealed no significant movement of the landslide from November 8, 2022, to the present. In total, portions of the landslide experienced >3 meters (>10 feet) of cumulative displacement since August 21, 2022.
Retrospective analysis of satellite data for the Barry Arm landslide reveals that this pattern of localized acceleration and slowing may be common. Other published studies at Barry Arm have identified ground movement at similar or much greater rates since 2008.
Localized ground movement is not necessarily a precursor to partial or complete failure of the Barry Arm landslide. Conversely, the current lack of observable ground movement is not a clear indication that hazards have significantly decreased. While our level of concern is reduced when the landslide is stable, other external triggers, such as a large nearby earthquake, could cause a rapid decrease in the stability of the landslide and a potential for catastrophic failure and the generation of a large tsunami. As such, the landslide remains a significant natural hazard in northwestern Prince William Sound.
(Last updated November 10, 2022)
There is a local monitoring network in Barry Arm that includes two seismometers, an infrasound array, a ground-based radar, several weather stations, and four cameras. Additionally, there is an infrasound array located in the town of Whittier, Alaska, approximately 50 km (31 miles) from the Barry Arm landslide. The National Tsunami Warning Center also operates three water level sensors in Barry Arm.
Systematic monitoring of optical imagery and remote sensing data, including satellite InSAR, is conducted throughout the year. New satellite observations are available bi-monthly with favorable atmospheric conditions; however snowfall will likely limit the use of InSAR analysis during the winter months.
There is currently no operational real-time warning system for the Barry Arm landslide and potential tsunami. Warning capabilities are currently experimental and subject to rigorous testing prior to being assigned an operational status. Updates on the status of the landslide as determined by current monitoring capabilities will be provided through the Alaska Division of Geological & Geophysical Surveys Barry Arm landslide webpage and email list (linked below).
The Barry Arm landslide is a large (~500 M m3 or 650 M yd3) landslide located in the northwestern corner of Prince William Sound, Alaska. Rapid, catastrophic failure of the landslide could generate a tsunami that would be life-threatening for anyone in Barry Arm, Harriman Fiord, and parts of Port Wells. Significant risks also exist in other, more distal locations of western Prince William Sound, including the town of Whittier, Alaska.
The existence of the landslide is evident in photographs dating back to at least 1937, with possible evidence of the landslide in photographs dating to 1913. Slow ground motion of the Barry Arm landslide has been documented going back several decades. Increased movement was documented during a period of rapid recession of the Barry Glacier from 2010 - 2016, with observed rates up to 26 ± 3 m/yr (85 ± 10 feet/yr) observed from May 2010 to September 2013. Deformation rates returned to a background level of approximately 1.3 ± 0.7 m/yr (4.3 ± 2.3 feet/yr) in March of 2017 as the retreat of the Barry Glacier slowed. Another period of movement was observed using aerial and satellite data in the fall of 2020 during which parts of the landslide moved over 3 meters (10 feet) between October 2020 and August 2021.
Alaskans should be aware of the ongoing risk and follow the advice of local emergency managers and harbormasters and have a plan in place if a tsunami occurs. Although there are several instruments operating near the Barry Arm landslide, a real-time landslide and subsequent tsunami warning system is not yet operational. From the National Tsunami Hazard Mitigation Program and the California Office of Emergency Services:
For a large, local-source tsunami that may arrive in 10-20 minutes:
In general:
The City of Whittier recently performed maintenance on and tested their existing tsunami siren and is investigating adding a second alert siren.
The Alaska Department of Homeland Security & Emergency Management (DHS&EM) provided the City of Whittier with new tsunami evacuation signage.
Coastal communities, mariners, and all visitors in Prince William Sound should remain informed, heed U.S. Coast Guard (USCG) and U.S. Forest Service (USFS) warnings to avoid the immediate area, and review emergency response and evacuation plans in the event of a tsunami. For more information, please contact your local emergency management authority and see these web resources:
If you have questions or more information about the Barry Arm landslide, we encourage you to reach out to DGGS via Facebook or Twitter, or by emailing barryarm@alaska.gov.
This message will be updated on April 7, 2023, or earlier if the threat level changes. For more information, please see our Barry Arm Summary Information & FAQ page.
