Damage from Mount St Helens lahar. House encased in mud from one of the lahars (volcanic mud flows) that followed the eruption of Mount St Helens on 18 May 1980. Mount St Helens is in Washington State, USA. The lahars consisted of material from the collapse of the northern flank of the volcano, mixed with glacier ice, snow and meltwater from the eruption. The lahars flowed down valleys in the surrounding area, demolishing trees, bridges and houses, and then solidifying like concrete. The lahars covered distances of nearly 30 kilometres at speeds of several kilometres per hour. This lahar travelled along the Cowlitz River. Photographed on 15 July 1980.