Volcano Eruption - Mt St Helens (MEDC)

Mt St Helens 1980 Eruption

Location

Mt St Helens erupted on the 18th of May 1980 in Washington State, USA. It's part of the Cascade Range Mountains. The eruption was catastrophic and the biggest one ever to hit the USA.

Causes

Mt St Helens is a volcano near the plate boundary between the Juan De Fuca and North American plates. This plate boundary was a destructive plate boundary because the plates were moving towards each other; the Juan De Fuca plate was being subducted below the North American plate. In the subduction zone, the Juan De Fuca plate was being melted in the mantle and the magama was rising up through the cracks in the North American plate, this formed Mt St Helens.

Mt St Helens erupted because of a magnitude 5 eruption near the plate boundary. The earthquake caused a bulge on the side of the volcano to collapse into an avalanche, this caused the volcano to erupt on that side because the rocks on that bulge were holding down magma in the magma chamber which was building up lots of pressure.

Predicting the eruption

• Tiltmeters were…