MULTI-SENSOR REMOTE MONITORING OF TSUNAMIGENIC LANDSLIDES IN THE BARRY ARM FJORD, ALASKA

Climate change has exacerbated the problem of slope instability related to degrading permafrost and glacier retreat, resulting in increased potential for landslide generated tsunami in steep-sided fjords. In Prince William Sound, Alaska, the rapid retreat of the Barry Glacier has led to the destabilization of landslides flanking the glacier. The largest of these landslides, on the order of 500 million cubic meters and over 2 kilometers wide, has the potential to generate a tsunami that would impact much of the Prince William Sound if it failed and rapidly entered the water of the fjord. Because of the size and complexity of the landslide, along with considerably challenging access and environmental conditions, remote sensing methods are an integral part of characterization and surveillance of landslide movement. These methods include bi-yearly airborne lidar, multi-week satellite-based and sub-hourly ground-based synthetic aperture radar (SAR), and image-based particle tracking via a high-resolution deformation camera. We find that deformation varies both spatially and temporally, from creep (5 mm/day) to intermittent movement (30 cm in 24 days), and landslide-wide to localized events. While some methods serve as a snapshot in time that is a culmination of events, others emphasize the ever-evolving nature of the landslide and the associated hazards. In the absence of in-situ validation, the use of multiple remote sensing methods has served to produce a detailed timeline of landslide deformation and rockfall events. These insights contribute to our understanding of landslide triggering conditions, and to tsunami early warning efforts.