A heavy rain event on August 18, 2015, triggered two landslides in the southeastern Alaska community of Sitka. The slides claimed three lives and caused substantial damage to property and infrastructure. Approximately 40 other slides occurred in the surrounding area on the same day. One outcome of the local, State, and Federal response to the disaster was the formation of the Sitka GeoTask Force, a multi-agency scientific work group that is studying the meteorological and geotechnical conditions leading up to the event to help the community better prepare for similar events in the future. As part of the task force, the NPS worked with the U.S. Geological Survey’s Commercial Remote Sensing Policy (CRSSP) and the Hazards Data Distribution System (HDDS) to provide new and archived satellite imagery to assist with the analysis of past landslide phenomena and the evaluation of future risk. In the months that followed the slides, over 120 Landsat 7/8 and WorldView 2/3 scenes were made available to participating agencies through the HDDS Explorer distribution portal. The imagery serves as a valuable resource for responders, community planners, and scientists by providing an inexpensive and detailed view of a large, remote area in southeastern Alaska. The imagery has been used by the task force to assess soil stability, update existing landslide inventory datasets, aid situational awareness for responders, and create predictive models of landslide hazards.
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Locations of landslides around Sitka, Alaska, August 18, 2015.