Barry Arm Landslide and Tsunami Hazard

 

Current Landslide Status

An ongoing landslide and landslide-generated tsunami threat exists in Barry Arm, northwestern Prince William Sound, Alaska. The landslide is stable or exhibiting slow rates of deformation (<50 mm/d). Localized areas of higher velocities may be evident, but movement is largely surficial. While potential failure of these areas may result in a localized tsunami, failure is unlikely to represent a region-wide tsunami threat. Partial or catastrophic rapid failure is unlikely without external forcing, such as that associated with a strong regional earthquake. "Small" but infrequent rockfalls and shallow landslides may be commonly observed.

Mariners should remain vigilant when in the vicinity of Barry Arm or nearby waters and be prepared to depart the area if any unusual rockfall activity is seen or heard, or if unusual waves, currents, or tides are observed.

Background

(Last updated February 2, 2024)

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 failure of the landslide has the potential to create a tsunami that results in life-threatening waves and currents in Barry Arm, Harriman Fjord, Port Wells and adjacent fjords. The existence of the landslide is evident in photographs dating back to at least 1935, with possible evidence of the landslide in photographs dating to 1913.

Throughout the observational record, the Barry Arm landslide has experienced slow movement punctuated by episodes of acceleration. While slow downslope movement is both common and expected, rapid increases in the rate of movement may be a possible precursor to catastrophic failure. As such, observations and hazard messages are often centered around trends in the observed rates of downslope movement at Barry Arm, as measured by ground-based, aerial, and satellite surveillance methods.

The Barry Arm landslide is being monitored by a multiagency team of scientists from the U.S. Geological Survey (USGS), National Tsunami Warning Center (NTWC), Alaska Division of Geological & Geophysical Surveys (DGGS), and the University of Alaska Fairbanks Alaska Earthquake Center (AEC). For more information on monitoring activities, equipment and data availability, please visit https://landslides.usgs.gov/storymap/barry-arm/.

Continuity of Operational Monitoring Network

(Last updated February 2, 2024)

Scientists at USGS, DGGS, AEC, and NTWC will continue to make every effort to minimize outage of this critical network of sensors. The Alaska environment and its inhabitants can wreak havoc on our sites: strong winds can damage sensors, power components, and antenna; deep snow can bury instruments and solar panels and makes it difficult to access (and even find) sites, rain can work its way into sensitive electronics, and our four-legged neighbors, such as bear, deer, and goats, have a taste for our wiring and enclosures. While we have made our best effort to harden the sensors, power systems, and telemetry for continuous operation of the equipment and to resist weather and animals, it is necessary to have reasonable expectations given the difficulties of working in this harsh environment. Reasonable expectations include:

• Safety of the scientists and engineers who maintain the systems is paramount. Poor weather conditions may prevent us from traveling to Barry Arm via helicopter or boat for immediate repair and restoration of system functionality.
• Prolonged outage of one or more sensors is possible. All efforts will be made to keep equipment operating throughout the year. However, high winds, deep snow, and other hazards such as snow avalanches and rockfall may prevent us from fixing instruments even if we are able to reach the sites.
• Deep snow, evolving snowpack, and variable atmospheric conditions make it difficult to precisely measure landslide deformation. As such, our ability to inform the public about landslide movement is significantly diminished during winter or when clouds or rainfall obscure the view from the air or space.

Instrumentation Status

Monitoring Method	Agency	Operational Status	Notes
Water Level	NTWC	Online	Occasional outages resulting from low voltage
Seismic - BAE	AEC	Online
Seismic - BAT	AEC	Temporarily Offline	Low voltage disconnect on 7 January 2024
Infrasound - BAEI	USGS	Online
Infrasound - WHTR	USGS	Offline, Permanently Decommissioned	Decommissioned as of 24 November 2023
Ground-Based Radar	USGS	Online	Operating at half time mode due to limited sun power
Deformation camera	USGS	Online
Satellite InSAR and imagery	USGS	Limited	Terrain obscured by snow (InSAR and imagery) and clouds (imagery)
Hydrometeorology - BAE	DGGS	Online
Hydrometeorology - BAW	DGGS	Online
Hydrometeorology - Mt Doran	DGGS	Online

Upcoming Fieldwork

DGGS will be conducting airborne geophysical surveys of snow and glaciers in late April in Barry Arm.

Upcoming Public Events - April 2024

• On April 9th, USGS scientists will be presenting "Tsunamigenic Landslide Hazards in prince William Sound, Alaska" at the Tuesday Night Talk hosted by the Prince William Sound Science Center. The presentation recording will be available here.
• Scientists from the USGS, NTWC, and DGGS will be attending the Prince William Sound Natural History Symposium on May 13th and 14th in Whittier, Alaska. Stay tuned for an updated schedule next month.

Next Update

This message will be updated on May 3, 2024, or earlier if the threat level changes. For more information, please see our Barry Arm Summary Information & FAQ page.