The Tsunami Generated by the October 17th, 2015 Taan Fjord landslide
Abstract
On October 17th, 2015, the largest landslide in North America in decades occurred in Taan Fjord, an arm of southeast Alaska's Icy Bay. The landslide triggered an enormous local tsunami. Flow indicators from satellite imagery suggest that the maximum tsunami runup immediately adjacent to the slide mass exceeds 190 m. Such a maximum runup would be second only to that created by the 1958 Lituya Bay landslide, a poorly recorded (by modern standards) event that is nonetheless the most important dataset for understanding extreme landslide tsunami hazards available to the engineering community. From numerical simulations and reconnaissance trips, we see widespread areas where the tsunami runup exceeds 100 meters in elevation. Furthermore, at least 90% of the 50 km of shoreline in the Fjord appears to have experienced runup elevations greater than 20 m.. With these large elevations comes large inundation distances. Often, the runup limit penetrated 10's to 100's of meters into dense brush and forest. Furthermore, along the edges of the trimlines, there was often a 3m+ high pile of debris consisting mostly of trees (see Figure). All of these factors make the tools of a common tsunami field survey - a laser rangefinder and a survey rod - effectively useless. Owing to this extreme runup and inundation distances, as well as the remote location, the team used a high-accuracy Real Time Kinematic (RTK) survey system, which provides 10-cm accuracy location elevations, after the data is tide-corrected. The types of data to be presented include the most-important runup elevations, flow depth profiles, areas of sediment scour and deposition, debris piles, and the impact of the tsunami on various types of vegetation.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMNH51D..05L
- Keywords:
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- 3225 Numerical approximations and analysis;
- MATHEMATICAL GEOPHYSICSDE: 4332 Disaster resilience;
- NATURAL HAZARDSDE: 4341 Early warning systems;
- NATURAL HAZARDSDE: 4564 Tsunamis and storm surges;
- OCEANOGRAPHY: PHYSICAL