FROM THE SUBARCTIC TO THE TROPICS – A COMPARISON OF TWO U.S. GEOLOGICAL SURVEY LANDSLIDE MAPPING EFFORTS (Invited Presentation)

Landslide inventories provide a basis for understanding landslide susceptibility and the role that landslides play in landscape evolution. Disparities exist in the quality of available landslide inventories and can be attributed to factors such as the availability of mapping resources, the magnitude of the triggering event, environmental conditions, and the purpose of the inventory. Here, we compare the efforts undertaken to develop the 2018 Southcentral, Alaska earthquake (M 7.1) ground failure inventory and the landslide inventory for the 2021 Nippes, Haiti Earthquake (M 7.2). The Alaska effort involved field and remote mapping and was developed to document ground failure (landslides and liquefaction) and improve USGS ground failure models. Mapping challenges included snow cover, limited daylight, and relatively subtle but widespread ground failures that were nearly impossible to discern in optical satellite imagery. Field observations and documentation of ground failure from government agencies was used to augment the inventory. The Haiti effort involved developing a landslide inventory from remotely sensed data and was used for situational awareness for humanitarian aid organizations. Some challenges included mapping coherent landslide movements, as they were visible only in high-resolution (0.3-0.5 m) imagery. Landslide dams in streams were numerous but assessing their risk to downstream populations with remote sensing data alone was difficult. Field reconnaissance was not possible, so it is likely that smaller landslides went unmapped. Data availability and quality, the ability to conduct field surveys, and environmental factors impact the extent to which remotely sensed data can be relied on to develop a high-quality inventory. A comparison allows us to understand the benefits and limitations of using remotely sensed data to map landslides in different environments and circumstances.