Top Banner

Click here to load reader

of 20

Lesson 2 volcanoes

Jan 16, 2015

ReportDownload

Documents

 

  • 1. VIOLENT VOLCANOES

2. What is a volcano?A volcano is an opening or vent in the earths surfacethrough which molten material erupts and solidifies as lava.Volcanic venthttp://www.youtube.com/watch?v=NBPwwt0HuVo&feature=fvst 3. Label this cross section of a volcanoVolcanic Crater bombs, ash,lava, gases Parasitic cone Main vent Volcanic bombs, ash, lava, gases Magma chamber Parasitic cone Magma Crater chamber Main vent 4. What comes out of a volcano? 5. Do all volcanoes erupt?Active volcano liable to erupte.g. Mt Etna & Mt. Merapi inIndonesia.Dormant (sleeping) volcano avolcano which has not erupted formany years. For example, MtPinatubo erupted in 1991 after 500years of dormancy. Extinct volcano a volcano which has not erupted for many thousands or millions of years e.g. Edinburgh.http://www.bbc.co.uk/learningzone/clips/volcanic-scotland/9116.htmlHowever, it is often very difficult to tell whether a volcanowill erupt againEl Chichon, Mexico erupted in 1982after being dormant for approximately 1200 years! 6. Why do they happen?Can you remember what is happening to the plates at aCONSTRUCTIVE plate boundary?The two plates are moving apartWhat comes up through the gap created in the crust?A volcano.Volcanoes at constructive plate boundaries dont tend to be veryspectacular or explosive. As the crust moves apart for themagma it is easily able to escape and just trickles out the top.The lava here tends to be runny and flows some distance fromthe crater before it solidifies. So, these volcanoes tend to beshallow sided, or SHIELD volcanoes. 7. Volcanoes also form at DESTRUCTIVE plate boundaries. Where one plate is forced down under the other (called subduction).What happens to the crust that is forced down into the mantle?It meltsWhat does this create?Excess magmaWhat do you think happens to this extra magma?Pressure builds and eventually there is a violent, explosive, volcanic eruption!Volcanoes at destructive plate boundaries tend to be very explosive! The lava is thickand so does not flow far from the crater. These volcanoes build up layers with eacheruption. These are called COMPOSITE volcanoes. 8. Example of a shield volcano- MaunaKea, Hawaii 9. Example of a composite volcano- Mt.Merapi Indonesia 10. Where in the world are volcanoes found? Around which plate do we find most volcanoes? 11. Where do Earthquakes and volcanoes form?The ring offire is anarea aroundthe PacificOcean, proneto A map to show theearthquakesRing of fire spread of Earthquakesand and volcanoes aroundvolcanoesthe earth 12. The Ring of Fire 13. Hawaii The Hawaiian islands are a chain of volcanoes in the Pacific Ocean. Look at their location on the map below. Why is this an unusual place for them to be located? 14. Hot spot volcanoesIn the animation above, why are the volcanoes to the left ofthe hot spot extinct? 15. HOT SPOT volcanoes are found in the middle of a plate.Here the crust is weaker than usual. There is a plume of hot magma rising fromthe mantle and it is able to push through the crust at this point.The plate moves across this hotspot forming a chain of volcanoes over millionsof years e.g. Hawaii. 16. Your tasks:You have one side of A3 paper on which to produce a fact sheet about volcanoes. You need to include:1. Completed pop-up volcano.2. An explanation as to how volcanoes form. Try to include information about both constructive and destructive plate boundaries and what the different volcanoes are known as (shield and composite).3. An explanation as to what is meant by active, dormant and extinct volcanoes.4. An explanation of hot-spot volcanoes.