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Animation showing the Mt St Helen’s eruption with text.
Thinking about volcanoes
The eruption of Mt St Helen’s USA, 1980. A Named example.
Make a table in your books… Causes of the eruption Effects of the eruptionCause is the reason something happens (Pressuremakes the volcano erupt).Effect is the result of what happens (The lava coversthe soil and kills the crops).
Mt St Helens eruption (May 1980)Mt St Helens is located on the ‘Ring of Fire’.
Mount St. Helens is located in Washington State, inthe Cascade mountains of the United States ofAmerica Mount St .Helens before the eruption
Mt St Helens – causes of the eruption Mt St Helens is located on a destructive plate boundary where a continental plate (North American) meets an oceanic plate (Juan de Fuca) Juan de Fuca plate North American plate
Why do they happen? A destructive plate boundary is found where a continental plate meets an oceanic plate The oceanic plate descends under the continental plate because it is denser. As the plate descends it starts to melt due to the friction caused by the movement between the plates. This melted plate is now hot, liquid rock (magma). The magma rises through the gaps in the continental plate. If it reaches the surface, the liquid rock forms a volcano Causes of eruption – write down on your map
The effects of the eruptionSpiritLaketurnedbrown withdust ashand lava.
A crater caused by one of the explosive lava ballsThe area aroundthe volcano lookslike the moon,stripped of alllife!
Mt St Helens – consequences of the eruption AFTERBEFORE
Mt St Helens – consequences of the eruption N 0 10km
http://www.youtube.com/watch?v=zp5MO77bFA4 Mt St Helen’s song!
Extended Writing• Imagine that you are a volcanologist. (A volcanologist is someone who studies volcanoes.)• As a volcanologist you have to produce a report for the volcano society regarding what happened to cause the eruption, what happened afterwards and what it was like during the eruption• You may want to include relevant diagrams/pictures.
HomeworkExtend the table already in your books. Using the followingslide, separate the effects of the eruption of Mt. St Helens intoshort term and long term.Causes of the eruption Effects of the eruptionShort term effects of the eruption Long term effects of the eruptionShort term effect is something that has changed but onlychanges for a little while and might change back to normal.Long term effect is something that has changed and will remainchanged for a long period of time or forever.
What damage did the eruption cause?Up to 70mm of ash falls across Washington and East Montana… 7000 schoolstudents have an early summer vacation due to problems on the roadsAn increase Mudflows block and divert rivers. The US army takesin tourism 18 months to dig out the debris from the River Toutle.Two million birds, animals Communications routes threatened – railway andand fish are killed. road bridges destroyed, Portland harbour blockedA decrease in Hot mudflows raise the temperature of 60 people die fromtourism the rivers and lakes to 30ºC the eruption. Gophers, through their tunnelling, mix the soilDeer mice, chipmunk, vole, with the ash. This increases the fertility of thegophers, salamander survive soil. Damage to crops=$175millionthe blast. Their populationsteadily increases due to the The post office and Lone Fir Motel shutabsence of predators. down in Cougar. In your table from the video, separate the above into the short term and long term impacts of the eruption.