Experimental volcanology on eruptive products of Unzen volcano

Protracted dome-building eruptions may be profitably investigated using laboratory-based experiments. Density distribution studies on the pyroclastic flow deposits of Unzen 1990-1995 allow us to apply the results of experimental investigations on Unzen samples to the interpretation of the last eruption of Unzen. Here, primary laboratory experiments have focused on several aspects of the degassing (permeability) and the fragmentation behavior (threshold, speed, and efficiency). Those investigations have been flanked by analyses of flexural strength, fracture toughness, and seismic velocities, to provide new insights into eruption related processes. Here we present a review of these results and their application to the eruption dynamics of Unzen Volcano. We propose that efforts be made to incorporate routinely such comprehensive experimental analyses into the response to emerging volcanic crises in future.