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Mt. St. Helen’s Washington State Katie Reibling & Jessie Radel. First signs of life. Thursday, March 20 th 1980 4.1 magnitude earthquake centered beneath the volcano. Most northwest newspapers completely ignored this earthquake
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Mt. St. Helen’sWashington StateKatie Reibling & Jessie Radel
First signs of life • Thursday, March 20th 1980 • 4.1 magnitude • earthquake centered beneath the volcano. • Most northwest newspapers completely ignored this earthquake • President Carter's announcement of the Moscow Olympics boycott dominated the news
March 27th-30th1980 • March 27th, first puff of ash. • The small explosion left a 250 foot wide crater in the otherwise perfect cone. • On March 30th there were a record 79 earthquakes recorded on the mountain
April 3rd 1980 • the first harmonic tremors were recorded signaling the movement of magma somewhere deep within the dome. • The crater was by now 1,500 feet wide. • Explosions of ash, rock and ice chunks were a daily occurrence.
The bulge • In April a noticeable bulge formed on the north side of the mountain. • Building of magma, hot gasses and pressure • Grew five feet per day
statistics • Largest land slide in history • 5.1 magnitude quake • Elevation dropped from 9,677 to 8,363 ft. • All of the rock ash melted snow and debris rushed down the mountain into the Toutle River Valley at speeds higher that 175 mph
Impacts • 57 People were killed • 5,000 black tailed deer,1,500 Roosevelt Elk, 200 Black Bears, millions of small animals • Toutle River valley • 3 billion dollars in damage
Plate Tectonics • The Juan de Fuca plate is subducting under the N. American plate • Magma moved into the shallow part of the volcano through out the many minor eruptions • So much pressure made the north bulge give out.
Will it Happen Again? • The slow collision of the North American Plate and the Juan de Fuca plate is causing the Juan de Fuca to slowly move beneath the Pacific Northwest • Scientists predict it will erupt again • they are not sure when or how much volcanic activities it will bring.
Monitoring Mt. St. Helens today • http://www.fs.fed.us/gpnf/recreation/current-conditions/
websites • http://www.olywa.net/radu/valerie/mshafter.html? • http://www.lincoln.smmusd.org/science/7th%20Grade/Earth/palosverdesfieldtrip/graphics/plate_boundaries.gif