Development of a global database of deposit-derived pyroclastic density current occurrences

The gravitational instability of glowing volcaniclastic deposits, whether it is the collapse of the crater rim or the failure of hot deposits on the flanks of volcanic cones, can give rise to so-called deposit-derived pyroclastic density currents (PDCs). These flows can remobilise volumes of 104 to 107 m3 and travel several kilometres from the source area. They are deposited at extremely high temperatures, posing a potential threat to nearby communities and tourists in the vicinity of volcanoes. Deposit-derived PDCs are much more widespread than originally thought, and two distinct phenomena have been documented: i) those induced by magma thrust; ii) those resulting from the collapse of hot material on the slopes of the volcano. In the latter scenario, loose volcaniclastic material can collapse due to factors such as exceeding the angle of friction or other mechanisms such as undercutting or overloading by volcaniclastic or lava flows. Deposit-derived PDCs have been documented at several sites. In all these events, glowing avalanches are reported to have formed from the remobilisation of poorly welded volcaniclastic agglomerates. Here we present a database, currently under construction, focusing on deposit-derived PDCs observed worldwide. The database is designed to collect information on the geographical distribution of occurrences, event dates, collapse mechanisms, remobilised volumes, flow types, deposit characteristics and bibliographic references. This effort is part of a larger project to elucidate the formation mechanisms and potential impacts of deposit-derived PDCs. Such knowledge will help to mitigate short- and long-term risks associated with these flows, contribute to the interpretation of monitoring data from active volcanoes, and inform appropriate land-use planning in their vicinity.