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Transcript of St. Helens
The reaction of authorities
They restricted any visits or passing through
They were quick to inform everyone about the accident
They kept the water level of the Spirit lake stable. Built a drain though the rock to allow the water to overflow and to avoid other complications
May 18, 1980
It is an active stratovolcano
Location: Pacific Northwest region (USA)
It is part of the Cascade Volcanic Arc
It is one of the 160 active volcanoes situated in the Pacific ring of fire
Elevation: 2,550 m
Age: 40,000 years
RQ: Can we limit the damage done by a volcano by examining its previous eruptions?
Mount St. Helens
The score after the event:
57 people were killed; 250 homes, 47 bridges, 24 km of railways and 298 km of highway were devastated, destroyed vegetation and buildings; over 600 km2
One of the most devastating eruptions in the history of USA
Predictions & Indicators
Juan de Fuca Plate
North American Plate
After the Juan de Fuca Plate melted, it created a magma chamber under the Earth´s crust from which the magma was continuously spilling out - forming a volcano of a conical shape
A touristic resort
A steaming monster
Occurs when magma damages the rock inside a volcano on its way to the surface
Awakened the volcano
The greater the pressure inside of volcano - the greater the intensity at which gas emissions escape and a more massive explosion can be expected
Deformation of its shape:
Possible accumulation of magma under its surface - formation of a huge bulge
"We did not know anything for sure until it happened."
-Dan Dzurisin, Geologist
Massive lateral blast - the northern part of St. Helens tore off and created a giant landslide - formation of a huge crater
Extermination of fauna and flora
Water weakened the rock and made the structure of the volcano less stable
As the water mixed with the soil it formed a gigantic mud flow (1448km/h)
Air pollution- St Helens created a giant mushroom cloud above itself full of ash, rock and hot gases
Blocked the exit of Spirit Lake
Advantages of this occasion
Allows scientist to study a magnificent event and involve techniques which can predict the next eruption more accurately
"What they have done in the past, is what they are going to do in the future." -Mike Clynne, Geologist
Helped save the lives of many in Caribbean (1995)
Possible epicenters of the earthqakes
David J. Bertuca. "Mount. St. Helens 2010: 30th Anniversary" UB Librerians. n.p., n.d. Web. 1.12.2012.
Anonym. "Mount St. Helens" Wikipedia. n.p., n.d. Web. 1.12.2012.
Geography Site. "Mt St. Helens" Geography Site. n.p., n.d. Web. 1.12.2012.
Unknown. "Explore Mount St Helens...Discover Ecosystems in Action" Mount St. Helens National Volcanic Monumen. n.p., n.d. Web. 1.12.2012.
Valerie Smith. "The many faces of " olywa.net. n.p., May 1998. Web. 1.12.2012.
Unknown. "MOUNT ST HELENS" BBC Earth. BBC, n.d. Web. 1.12.2012
Dorling Kindersley Book. Student Atlas. London: Dorling Kindersley Limited, 2002. Print.
mtb3241, 1980 The Mount Saint Helens Eruption. (04.04.2010) http://www.youtube.com/watch?v=d Bm9kTSrxio. 1.12.2012
999yellowstone, How The Earth Was Made.Mt St Helens. (07.10.2011), http://www.youtube.com/watch?v=M4PsTPEaeRI. 1.12.2012
Monika Očková, MYP4