Lahars

Volcanoes like Soufrière Hills produce lots of volcanic ash when they erupt. That’s why the summits of many volcanoes are covered by a thick layer of ash. Rainfall can remobilise this ash to form so-called mudflows or lahars. This are mixtures of water, ash and other volcanic debris, running down the volcanoes following river channels and destroying everything in their path.

Caption: A lahar in the Belham Valley in 2004. The vehicle was eventually swept away. Credit: MVO Archive. Location: Belham Valley. Date: 9/11/2004

Lahars can occur years after volcanoes stopped erupting, making them an especially dangerous hazard. In Montserrat, heavy rainfall is common, and so are lahars. The video below shows a lahar in Belham Valley in 2016.