Real-time Detection and Insights From the September 2024 Surprise Glacier, Alaska, Landslide Sequence
Description:
On September 20, 2024, a series of repeat landslides above the terminus of Surprise Glacier in Prince William Sound, Alaska, triggered a small tsunami that was detected in real-time — a first for landslide-generated tsunamis in the region. The landslides were identified using seismic data and later corroborated with satellite imagery, tide gauge readings, and infrasound observations. Although Surprise Glacier has experienced rapid retreat over the past year, analyses done before this landslide sequence did not indicate any evidence of precursory deformation at this location. Even though the retreat has contributed to slope instability, our analysis suggests that an intense period of rainfall immediately preceding the landslides was likely the primary trigger.
We present the detection and interpretation of the Surprise Glacier landslide sequence, focusing on the integration of diverse geophysical data streams collected within hours after the event, as well as detailed modeling performed in the days and months that followed the sequence. An experimental seismic monitoring system successfully triggered detection alerts within three minutes of the main landslide, using stations located 20 to 250 km from the source. Infrasound signals from a nearby array, located 20 km away, corroborated the event’s location approximately 30 seconds after the seismic arrival, and the tide gauge 16 km away confirmed a tsunami wave 12 minutes later. A subsequent landslide seismic force inversion and seamless landslide-tsunami simulation, as well as imagery interpretation, provide further insights into the landslide’s dynamics, failure sequence, and implications for hazard assessment. This interdisciplinary approach underscores the critical role of seismic monitoring in early warning and hazard response, complemented with strategically placed instrumentation to further mitigate risk in vulnerable regions.
Session: Geophysics in a Changing World: Monitoring Applications from Seismology and Beyond - I
Type: Oral
Date: 4/15/2025
Presentation Time: 04:30 PM (local time)
Presenting Author: Ezgi
Student Presenter: No
Invited Presentation:
Poster Number:
Authors
Ezgi Karasozen Presenting Author Corresponding Author ekarasozen@alaska.edu University of Alaska Fairbanks |
Michael West mewest@alaska.edu University of Alaska Fairbanks |
Katherine Barnhart krbarnhart@usgs.gov U.S. Geological Survey |
John Lyons jlyons@usgs.gov U.S. Geological Survey |
Terry Nichols terry.nichols@noaa.gov National Tsunami Warning Center |
Summer Ohlendorf summer.ohlendorf@noaa.gov National Tsunami Warning Center |
Lauren Schaefer lschaefer@usgs.gov U.S. Geological Survey |
Dennis Staley dstaley@usgs.gov U.S. Geological Survey |
Gabriel Wolken gabriel.wolken@alaska.gov Alaska Division of Geological & Geophysical Surveys |
Real-time Detection and Insights From the September 2024 Surprise Glacier, Alaska, Landslide Sequence
Session
Geophysics in a Changing World: Monitoring Applications from Seismology and Beyond