Hazards of large volcanic debris avalanches and associated eruptive phenomena

摘要: Slope failures resulting from structural instability of volcanoes produce extremely mobile debris avalanches that can travel long distances beyond the flanks of volcanoes at high velocities. Large mass movements occur at volcanic constructs ranging from lava dome complexes to massive shield volcanoes, creating horseshoe-shaped reentrants into the edifice that can attain caldera-sized dimensions. More than 20 major slope failures have occurred globally during the past 500 years, a rate exceeding that of caldera collapse. Debris-avalanche deposits are the dominant volcaniclastic component at some volcanoes. Their widespread occurrence in a variety of tectonic settings suggests that slope failure may be the dominant catastrophic edifice- modifying process. Debris avalanches typically form hummocky deposits of largely unsorted and unstratified angular-to-subangular debris, although deposit …