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Terminology and Strategy to Describe Large Volcanic Landslides and Debris Avalanches

Abstract:

Large volcanic landslides and debris avalanches are rapid, water unsaturated, gravity-driven mass movements produced by the failure of one (or more) portion(s) of a volcanic edifice. In this chapter, we evaluated the current terminology used to describe this phenomenon. We propose a descriptive scheme based on metrics and geological features that allows us to extract significant information from both the source area and the deposit. The landslide scar is a breached depression in the volcanic edifice with steep walls, and the debris avalanche deposit is an epiclastic, unsorted, heterogeneous and heterometric breccia, composed of pieces of the edifice source, the transport path, and sometimes the basement/substratum of the volcano. Typical structures, such as jigsaw cracks and hummocky topography, along with some rarer descriptive elements are illustrated with numerous examples. This work aims to improve field analysis and remote sensing and to enhance comparative studies between different events around the world.