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.

Highlights of Recent Activity

During the week of May 11, scientists from the U.S. Geological Survey (USGS) and Alaska Division of Geological & Geophysical Surveys (DGGS) gathered at the Alaska Volcano Observatory (AVO) for a three-day workshop focused on the direct and cascading hazards of large, bedrock landslides, such as the one in Barry Arm and the recent landslide and tsunami in Tracy Arm. This collaborative effort is intended to provide a scientifically defensible method for assessing the potential for rapid catastrophic failure of slow-moving landslides, characterize their potential impact, and quantify the degree to which the dynamic Alaska environment affects their potential hazard now and in the future.

During the week of May 18, scientists from the USGS completed the annual spring maintenance of the ground-based radar system in Barry Arm. We made several upgrades, including installing a new fuel cell and new batteries to improve function and connectivity over the winter months. This upgrade occurred alongside the annual tasks of swapping over the summer fuel supply and routine system checks.

At the same time, staff from the National Tsunami Warning Center (NTWC) replaced a pressure sensor at the north shore tide site and improved the telemetry at Point Doran. Snow levels and weather did not permit access for the maintenance at the high elevation weather sites operated by DGGS. This maintenance has been rescheduled for later in the season.

Upcoming Fieldwork

• No fieldwork planned for June 2026.

Instrumentation Status

Monitoring Method	Agency	Operational Status	Notes
Water Level	NTWC	Online
Seismic - BAE	AEC	Online
Seismic - BAT	AEC	Offline	Weather-related telemetry issues
Infrasound - BAEI	USGS	Online
Ground-Based Radar	USGS	Online	Intermittent weather-related telemetry issues
Deformation camera	USGS	Online
Satellite InSAR and imagery	USGS	Limited	Snow-on conditions and cloudcover
Hydrometeorology - BAE	DGGS	Online
Hydrometeorology - BAW	DGGS	Offline	Decomissioned
Hydrometeorology - Mt Doran	DGGS	Online

Upcoming Public Events

• No upcoming public events in June 2026.

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.

Recent Publications

• A collaborative publication documenting the August 11, 2025 Tracy Arm landslide and tsunami was published on May 6, 2026, at the journal Science
• Mike West and Ezgi Karasozen from the University of Alaska Fairbanks Alaska Earthquake Center published an editorial on landslide detection and early warning in The Conversation

Next Update

This message will be updated on July 3, 2026, or earlier if the threat level changes. For more information, please see our Barry Arm Summary Information & FAQ page.