DOCUMENTING MEGA-LANDSLIDES IN THE BASIN AND RANGE USING THE MYHAZARDS AND MYPLAN WEB MAPPING APPLICATIONS

Dozens of mega-landslides (area >1 km²) have been identified within the Basin and Range province. Most of these features have been mapped at least at the 1:100,000 scale and are included within county geologic maps or other reports. A few of the mega-landslides and landslide complexes have had extensive work completed on them, but most have only been mapped. Undoubtedly, there remain unidentified large-scale landslide deposits, potentially including isolated bedrock blocks within valley fill and buried mega-landslides. Although these features are fairly ubiquitous in the Basin and Range, their presence and hazard potential remain underappreciated.

To remedy this, we are building a mega-landslide database and map layer that will be available through the MyHAZARDS and MyPLAN web mapping applications. The Nevada Bureau of Mines and Geology (NBMG) hosts data on geologic hazards in Nevada through these web apps on their website. The MyHAZARDS web application is geared towards the public, whereas the MyPLAN application was developed as a tool for emergency managers and requires a log in. These data are presented as interactive ArcGIS maps and include hazards related to earthquakes, fires, volcanoes, floods, radon, and droughts. One layer from the USGS on landslide susceptibility is available, but it is mapped at a national level and provides no information on individual landslide events. Therefore, this new layer adds information on the mega-landslides and historic landslides to the NBMG database. The data incorporated into the layer include accurate polygons, short summaries of the known information about the landslides, key geomorphometric characteristics, and links to published information. These data will be periodically updated as new maps and publications on mega-landslides become available. Ultimately these data will be of value to researchers, emergency managers, and the general public.