Monitoring Efforts at the Barry Arm Landslide

Last updated: February 6th, 2024

Rockslides located in steep-sided fjords can pose significant hazards to nearby communities and boat traffic through their ability to generate  large tsunami waves . The Barry Arm landslide, located in northwestern Prince William Sound on the northwest side of Barry Arm in Harriman Fjord, Alaska, and about 30 miles (48.3 kilometers) from the coastal town of Whittier, could pose such a threat if the slope were to fail catastrophically.

The retreat of Barry Glacier, which once stretched along the base of Barry Arm Landslide, has resulted in open water now extending beneath the landslide. The hazard posed by the landslide raises questions about its stability and the potential cascade of hazards that could occur after catastrophic failure. To monitor this hazard and provide up-to-date information to local residents and emergency and land management groups, an interagency team was formed. The U.S. Geological Survey (USGS), Alaska Department of Geological and Geophysical Surveys (DGGS), National Oceanic and Atmospheric Administration (NOAA) National Tsunami Warning Center (NTWC), Alaska Earthquake Center (AEC), and Alaska Department of Homeland Security and Emergency Management (DHSEM) have partnered to install equipment to monitor Barry Arm landslide and perform additional analyses on other slopes in Prince William Sound.

To understand Barry Arm's susceptibility of rapid landsliding, a wide array of instrumentation was depoyed to collect, store, and analyze data to understand what conditions indicate stability, and which indicate dangerous instability. These instruments include seismic data to pick up local earthquakes and other activity, radar images to capture how the landslide is moving, images to provide situational awareness, and more. What follows are descriptions of some of the equipment that has been installed, as well as a map of instrument locations.

Two full meteorological stations with cameras and six smaller meteorological stations (nodes) were installed to continuously monitor weather near the landslide.  One full meteorological station  and four nodes were installed on the west side of the fjord above the landslide (designations beginning with BAW), and  one full meteorological station  and two nodes were installed across the fjord (designations with BAE). These stations monitor weather conditions such as rainfall accumulation and solar radiation and allow us to understand baseline conditions so that we may understand what might initiate a failure. Click on the hyperlinks for each full meteorological station to view the data in real-time.

A six-element infrasound array was installed in the winter of 2021 near Whittier. The array is used to detect sound waves generated by several geologic hazards. These low frequency sound waves can travel long distances and are useful for detecting and characterizing large landslides.

In the summer of 202, a second six-element infrasound array ( BAEI ) was installed across the fjord from the Barry Arm Landslide, near the full BAE meteorological station. Click on the hyperlink to view the data in real-time.

These data can be used to identify mass movements, such as rockfall, debris-flows and shallow landslides, that may indicate increasing landslide activity, or the catastrophic failure of some or all of the Barry Arm landslide. In addition, the data may also provide insights into processes related to the movement of nearby glaciers, and the occurrence and characteristics of other landslide- and volcano-related events in the region.

Ground-based radar, co-located with BAE node 1, is used to observe the landslide and characterize the kinematics that inform on slope stability. This instrument allows for the precise measurement of centimeter-scale movement of the landslide over a range of time scales. The radar is situated on a ledge system on the east side of Barry Arm, opposite the landslide.

Three seismometers were installed near the Barry Arm landslide by AEC. These instruments are used to measure ground motions that may indicate movement of the Barry Arm landslide, as well as potentially pick up landslide activity in other parts of Prince William Sound. Data are transmitted in real-time and managed by the Incorporated Research Institutions for Seismology. Two seismometers were installed in October 2020, one on the ridgeline on the opposite side of the fjord from the Barry Arm landslide ( BAE ), and one on the landslide mass (BAW). BAW was destroyed by a snow avalanche in April 2021. A third seismometer was installed as a replacement at a safer site along the ridgeline above the landslide ( BAT ). These stations augment the existing seismic network in the region run by AEC and NTWC. Click on the hyperlinks attached to the abbreviations to view real-time data from each station.

NTWC operates a local sea level monitoring system designed to detect a  tsunami  generated by a failure of the Barry Arm. These data are a crucial piece in the chain of monitoring and warning. For now, the sea level monitoring network at Barry Arm is still experimental in nature, and several tests and robustness requirements still need to be passed prior to the instrumentation network being considered an operational emergency warning system.

Communication in Harriman Fjord where Barry Arm is located is limited. Telemetry was installed on Mount Doran to transmit data collected at the meteorological stations, seismometers, and radar sites. These data are transmitted by cellular networks to servers at the USGS, AEC, and NTWC in Alaska, California, and Switzerland where the ground-based radar is serviced. NTWC sea level sensor data are transmitted via cellular network from the Packenham site (BA1).

Below is a map tour showing the locations of the instruments discussed in this section. Click on a location or a picture to find out where it is and what it does.

In addition to field instrumentation, remote sensing - or data acquired from planes or satellites - is used to map and monitor Barry Arm Landslide. Remote imagery complements field data, as it provides information over the entire landslide. Both aerial lidar (light detection and ranging) and satellite InSAR (interferometric synthetic aperture radar) are being used at Barry Arm. 

Lidar measures the ground surface with lasers to create digital three-dimensional (3-D) representations of the Earth’s surface. The  resulting high-resolution maps  can be used to  map landslide features and track changes in the landslides over time .

InSAR uses two satellite radar images taken at different times to generate maps of landslide movement.  These data  are used in snow-free months to determine the location and amount of landslide movement. In October 2020, InSAR measured up to 11.8 inches (30 cm) of downslope movement on the landslide. This movement, as well as the installation of the first seismometers, prompted the development of a monthly interagency science team  status report  to alert the public to any potential changes in the landslide and tsunami hazard status.

Part of the characterization of potentially unstable rock slopes in the Prince William Sound region depends on measuring the strength qualities of the rock forming the slopes.  To capture these data, a team of scientists travelled around PWS by boat and helicopter to make measurements of rock characteristics.  They visited multiple rock outcrop locations each day, and at each site, assessed rock mass quality and other geological characteristics. These data can inform regional rock-slope hazards in Prince William Sound. 

On July 21, 2021, the Whittier Public Safety office held a workshop to engage members of the local community and educate them on the hazards and activities related to the Barry Arm landslide.  Scientists from the USGS, Alaska DHSEM, and NOAA shared educational materials about tsunamis, earthquakes, and landslides. The USGS provided a  brief summary on a recent data release  about the simulated tsunami wave height and the fieldwork being conducted. 

In July 2021, USGS scientists spoke with Whittier residents at the workshop and interviewed local business owners to receive feedback on the scientific communication efforts thus far. This feedback is being taken into consideration for future communication efforts.

On May 23, 2022, USGS scientists attended the Prince William Sound Natural History Symposium to speak about the current monitoring efforts and science updates in Barry Arm and Prince William Sound.

In July 2022, USGS scientists interviewed Whittier residents to gain a better understanding of what residents know about tsunami preparedness and the Barry Arm landslide, what gaps needed to be filled, and what methods of communication were most effective. The results from these interviews can influence upcoming outreach efforts in Whittier and Prince William Sound.

In May 2023, scientists from several agencies attended the Prince William Sound Natural History Symposium to speak about the current monitoring efforts and science updates in Barry Arm and Prince William Sound. They also conducted K12 outreach at Whittier Community School and held a community outreach event in Whittier.

In September 2023, USGS scientists conducted school outreach at Valdez middle and high school, as well as at Prince William Sound College. They also held a community outreach event in Valdez.

In addition to the monitoring efforts detailed above, the USGS and interagency partners are working to keep the public informed on potential changes to the landslide and tsunami hazard status. This information  is posted as a monthly status report by DGGS .

Originally a tool for outdoor enthusiasts to keep record of their adventures, the  Mountain Hub app  has gained new life as a tool for federal scientists and citizen scientists alike to record their observations of geohazards and landscape changes they notice in their adventures. Explorers can record possible hazards they see with notes and photos to aid scientists in their mapping and logging of Alaskan geohazards. A landslide observation tool is being developed in the Mountain Hub app to help scientists gain data specifically on landslides throughout Prince William Sound as we assess landslides and associated tsunami hazards in the region and Alaska.