Volcanic eruptions are sometimes accompanied by clouds of ash and hot gases that travel down the slopes of volcanoes at tens of kilometres per hour. These clouds, called pyroclastic density currents (PDCs), are some of the deadliest volcanic hazards. And as we cannot easily study them in real-time, we took another approach to quantify some of the features that make them so dangerous: their speed, temperature, height, and how far they travelled.

On 25 October 2010 at 9:42 PM local time, the people living on the southern Mentawai islands, a chain of islands located off Sumatra, Indonesia, felt a slow, gentle rocking of the rocks below their feet. Initial reports of the earthquake indicated that a magnitude-7 to -7.2 earthquake had occurred seaward of the islands.

Lying at the junction of several tectonic plates, Myanmar is exposed to geohazards such as earthquakes, tsunamis, and volcanic eruptions. To help prepare for these hazards, scientists produce hazard assessments using their understanding of the region’s geology and tectonic activity. They seek to answer questions such as: how do the tectonic plates interact with each other, how deep the magma is, where the faults are, and what kinds of earthquakes can we expect?