DOI: 10.5066/p1gpflbn
title: Preliminary Locations of Landslides and Snow Avalanches Triggered by the 2025 M7.0 Hubbard Glacier Earthquake

description: This data release contains preliminary point locations of potential landslides and snow avalanches triggered by the M7.0 Hubbard Glacier Earthquake based on a Synthetic Aperture Radar (SAR) change map by Eiden (2025). This SAR change map reflects changes in the backscattering properties of the surface by comparing  Sentinel-1 SAR acquisitions from before (11/28/2025) and after (12/9/2025) the earthquake. Many types of surface change impact backscattering properties in a snowy, mountainous environment including landslides, snow avalanches, new snowfall, changes in surface moisture, glacier movement and more (Lindsay and others 2025, Rott and Mätzler, 1987). By combining these change detection data with topographic maps and regional information, we are able to map where surface change is likely related to mass movements such as landslides and snow avalanches.

We focused on assessing the areas where the USGS near-real-time earthquake-triggered Ground Failure Product estimated landslides were likely, based on the ShakeMap shaking estimates and proxies for landslide susceptibility. The exact boundaries of the mapping area are provided in shapefile format in Hubbard_LSmapping_boundary.zip and mapped points in Hubbard_LSlocations.zip. Mass movement points were mapped where the shape of patches of increased roughness aligned with the topography in a way that is consistent with gravitational flow behavior. For example, the footprint should typically be elongated in a direction that is perpendicular to contour lines of topographic elevation. We found we could primarily detect changes in roughness due to the deposition of snow, ice, or rock onto glaciers and could not see changes in the source areas. Therefore, we placed the location points at the most uphill portion of the patch of increased roughness based on a reference topography map.

The “interpretation” attribute defines our interpretation of each mapped location and its certainty as follows:
1 (probable large landslide): the shape of the patch of increased roughness and its alignment with topography is consistent with a large landslide, likely a rock avalanche or rock and ice avalanche, that is at least 2 km long and shows well-defined boundaries with lobe-shaped toes that are typical of rock avalanche deposits onto glaciers (e.g., Bessette-Kirton and Coe, 2020).
2 (probable smaller landslide or snow avalanche): the patch of increased roughness is sufficiently well-defined and away from areas of noise or poor data quality such that we are relatively certain it reflects a mass movement of some type, but it is small enough (less than 2 km long) that it could be either a landslide or a snow avalanche.
3 (increase in surface roughness of undetermined origin): this level is assigned to patches that are aligned with topography in a way typical of a mass movement, but may have less well-defined edges (e.g. speckled), may be smaller or similar in character to noise nearby, or may be hard to distinguish from areas adjacent to areas of low data quality. This also includes potential glacier movement that is hard to distinguish from mass movement deposits.
We note that the direction of satellite movement combined with the look angle of the satellite means we are not able to reliably detect changes on steep southwestern and western-facing slopes due to foreshortening. Therefore, mass movements are likely less comprehensively mapped on southwest- and west-facing aspects.