Hot science from a volcanic crisis

摘要

Thirty years ago this week, Mount St Helens in Washington state was swollen to bursting point. The northern flank of the mountain was bulging outward at a rate of more than one metre per day as magma built up inside. By 18 May 1980, the volcano could withstand the pressure no longer. The side of St Helens collapsed in an immense landslide, unleashing the largest explosive eruption in US recorded history.rnAn avalanche of rock raced 22 kilometres downhill while a plume of debris shot 25 kilometres skyward, punching into the stratosphere. The eruption killed 57 people near the volcano and blanketed 10 states with a layer of ash.