HISTORICAL ROCK FALLS IN YOSEMITE NATIONAL PARK, CALIFORNIA (1857-2011): AN UPDATED INVENTORY OF ROCK FALLS AND OTHER LANDSLIDES

Inventories of rock falls and other types of landslides are valuable tools for improving understanding of these events. Rock falls represent a significant natural hazard in Yosemite National Park, California, particularly in Yosemite Valley where glacially steepened granitic cliffs approach 1 km in height and where the majority of the approximately 4 million annual visitors to the park congregate. In addition to damaging roads, trails, and other facilities, rock falls have killed 15 people and injured at least 85 people in the park since 1857 when the first written observations began. The National Park Service and U.S. Geological Survey recently completed an updated inventory of rock falls and other types of landslides (e.g., rock slides, debris slides, debris flows) in Yosemite National Park. The inventory database documents 925 events spanning the period 1857–2011. Each event includes information on location, type of event, date, time, volume, relative size, probable trigger, preceding environmental conditions (temperature and precipitation), impact to humans (fatalities, injuries, and/or infrastructure damage), and any other published references. The inventory database is contained in an easily sortable Microsoft Excel spreadsheet, allowing for statistical insights into rock-fall susceptibility and environmental triggering conditions. Each event also contains a written narrative that includes additional descriptive information in an easy-to-read pdf file. The database and accompanying report are available at http://pubs.usgs.gov/ds/746/.