MAPPING MASS WASTING HAZARDS ON ANNETTE ISLAND RESERVE, ALASKA
We analyzed topography from lidar data collected in 2016 and 2018 along with geologic maps, precipitation information, and the presence of recent failures to categorize the landscape into zones of varying hazard. Preliminary results show that despite the steep, glaciated topography of the mountainous island, evidence for mass wasting events appears to be limited to shallow landslides and debris flows. These events tend to not be limited to a single type of bedrock, and are found on steep forested slopes along the flanks of U-shaped valleys. While analyzing the lidar data the absence of large deep-seated slumps which are sometimes common in very mountainous setting, suggests that the rocks on this island are relatively strong, and there is a lack of substantial quaternary deposits that drape the local topography.
The results of this work will inform land managers on the island about the possibility of disruption from future mass wasting events. Results may be applicable to similar landscapes that are mostly devoid of quaternary deposits. The results of making a hillslope hazard map will give the residents of Metlakatla a sense of where these mass wasting events happen, and where potential landslides could occur