Post-eruptive outburst floods from caldera volcanoes and lahar hazards

Abstract

Catastrophic outburst floods by a breach of volcanic dam or caldera rim tend to be hazardous with voluminous impounded water and loose unconsolidated pyroclastic material. Such extreme floods can travel long distance from the source volcano that ultimately affect landform and hydrology of downstream areas and eventually threaten human life and economy. Tohoku area hosting active volcanoes is susceptible for such a catastrophic flood by dam break as shown by two examples from Numazawa and Towada calderas.