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Mt St Helens

Mt St Helens, USA

Mt St Helens, USA

Local name: Mt St Helens
Largest recorded eruption:

Last eruption:

Mount St Helens is the most active volcano in the Cascade range, Washington, USA. It was built in four eruptive stages beginning 275,000 years ago and activity has oscillated between explosive and effusive eruptions. Its distinctive conical appearance was destroyed by a huge eruption in 1980 when a flank collapse was followed by a massive lateral blast; the modern day volcano consists of a horseshoe-shaped crater partially filled by a lava resurgent lava dome. Lavas from the 1980-1986 are some of the most studied eruptive products in the world, and CRITMAG-funded research has focussed on using dacitic samples for experimental phase relations and diffusion chronometry.

Related CRITMAG publications
Smithsonian webpage