GIANT LANDSLIDES, TOPOGRAPHY, AND EROSION

Abstract

Distributions of slope angles in tectonically active mountain belts point to the development of threshold conditions, where hillslopes attain a critical inclination or height at which they fail readily because of limitations in material strength. It has been proposed that hillslopes adjust to rapid uplift and bedrock incision through an increase in the rate of relief-limiting landsliding rather than gradual slope steepening. Here we test this concept by investigating the relationship between mean local relief H¯, which we take to be a proxy of long-term erosion rates E, and the occurrence of over 300 of the largest (V > 108 m3) terrestrial landslides on Earth. We find that nearly two-thirds of these giant landslides have occurred in the steepest 5% of the Earth's land surface, where relief is close to its proposed upper strength limit. They are primarily located in deeply incised valleys, along fault-bounded fringes of active mountain belts, and in volcanic arcs.