Rapid Seismic and Infrasonic Assessment of a Large Landslide in Denali National Park (Alaska) Aided by Aerial and Satellite Imagery and Numerical Flow Modeling
Description:
On September 13, 2023, at 6:06 PM local time, a large rock–ice avalanche occurred in Denali National Park (Alaska). Unlike many remote Alaska landslides, this event was rapidly detected. A tourist flightseeing operator noted a dust cloud in the area, and seismic signals generated by the landslide were detected by real-time earthquake monitoring systems operated by the Alaska Earthquake Center (AEC) and National Earthquake Information Center. An AEC-hosted seismic landslide detection tool provided a location and a preliminary size. The landslide also generated significant infrasound (low-frequency atmospheric sound) waves which were recorded at distances exceeding 250 kilometers. The following morning, park staff — equipped with the initial seismic parameters — flew to the landslide and took aerial photographs.
To determine the failure timeline and dynamics of this landslide, we use long-period seismic signals to infer the time-varying force vector f(t) exerted by the landslide on the Earth. We process infrasound array data to determine the timing and back azimuth of multiple failure signals recorded on four arrays located across Alaska. We reconstruct the failure using the numerical flow model SHALTOP, constraining the model output with f(t) and deposit morphology measured from aerial and satellite imagery. Our analyses reveal that
•two smaller pre-event slides occurred eight and three minutes prior to the primary failure;
•the primary failure consisted of three to six million cubic meters of rock and ice which broke free at a steep angle before traveling to the north-northwest about three kilometers, creating abundant dust; and
•the source region was still producing seismogenic post-event slides eight days after the main failure sequence.
This well-recorded event motivates re-examination of current detection, location, and characterization capabilities for large, rapid, remote landslides. With an eye towards operational monitoring and streamlined event response, we will highlight some "lessons learned"from our multi-institution response which are broadly applicable to this class of remote hazards.
Session: Geophysics in a Changing World: Monitoring Applications from Seismology and Beyond [Poster]
Type: Poster
Date: 4/15/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Ezgi
Student Presenter: No
Invited Presentation:
Poster Number: 47
Authors
Liam Toney Corresponding Author ltoney@usgs.gov U.S. Geological Survey |
Michael West mewest@alaska.edu University of Alaska Fairbanks |
Ezgi Karasozen Presenting Author ekarasozen@alaska.edu University of Alaska Fairbanks |
Dennis Staley dstaley@usgs.gov U.S. Geological Survey |
Denny Capps denny_capps@nps.gov National Park Service |
Elaine Collins ecollins@usgs.gov U.S. Geological Survey |
Kate Allstadt kallstadt@usgs.gov U.S. Geological Survey |
Heather McFarlin hlmcfarlin@alaska.edu University of Alaska Fairbanks |
John Bellini bellini@usgs.gov U.S. Geological Survey |
Matthew Haney mhaney@usgs.gov U.S. Geological Survey, Anchorage, Alaska, United States |
David Fee dfee1@alaska.edu University of Alaska Fairbanks, Fairbanks, Alaska, United States |
John Lyons jlyons@usgs.gov U.S. Geological Survey, Anchorage, Alaska, United States |
Anne Mangeney anne.mangeney@gmail.com Paris Cité University, Paris, France |
Rapid Seismic and Infrasonic Assessment of a Large Landslide in Denali National Park (Alaska) Aided by Aerial and Satellite Imagery and Numerical Flow Modeling
Session
Geophysics in a Changing World: Monitoring Applications from Seismology and Beyond