Book excerpt: This book presents an overview of volcanic debris avalanche deposits, which are produced by partial volcanic edifice collapse, a catastrophic natural phenomenon. It has been 40 years since the volcanic debris avalanche associated with the 1980 eruption of Mount St. Helens, and our understanding of these events has grown considerably in the interim. Drawing on these advances, the book addresses all aspects of volcanic debris avalanches. Though previously overlooked in field-based geological and volcanological studies, these deposits are now known to be associated with most volcanoes and volcanic areas around the world. The book presents state-of-the-art ideas on the triggering and emplacement mechanisms of these events, supported by field and analogue studies, as well as new simulations tools and models used to determine their physical characteristic and hazards.