Topic:Tectonic Hazard - Volcano Case Study: MEDC – Mount St. Helens - 1980 Location:Washington State, North West USA. Cascade Mountain range) Geographical Keywords • Nuée ardente - the superheated gases found in a pyroclastic cloud. • Pyroclastic flow- the cloud of gas, ash, dust, stones and rocks emitted during a highly explosive volcanic eruption. • Lahars - mudflow associated with volcanic activity. Surface water mixes with volcanic ash to produce the lahar. • Cryptodome – A hidden dome of magma under the surface of a volcano. Often to the side of the main vent. • Volcanic plug – A blockage of rock and ice in the main vent of the volcano • Magma – molten rock found under the earths surface
