EES-1000 Lecture 20: Lecture Notes 6
7 Oct 2016
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Volcano architecture: lava dome- rounded, steep changed slide! Ex: mount st. helens (washington): crater- a bowl-shaped depression atop a volcano, are up to 500 m across; 200 m deep, form as erupted lava piles up around the vent, caldera- a gigantic volcanic depression! Yellowstone- most recent, large eruption occurred 640,000 years ago. Volcanic hazards: lava flows- lava threats are mostly from basalt, ashfall around the volcano! It is rare for lava ows to kill people. Can completely bury landscapes, killing plants and crops! This material is gritty; it abrades car and airplane engines! Water easily moves tho material as deadly mud ows! Large masses of material are deposited rapidly near vent! The eruption immediately followed a slope failure: lahars- mud ows result when ash is moved by water! Ex: nevada del ruiz, colombia: earthquakes- causes by moving magma, tsunamis- water explosions create giant waves, gas- volcanic gases are poisonous (h2s, co2)! Active vs. extinct: recurrence interval- average time between eruptions!
