VOLCANOES
Pompeii, Italy
Bodies…
Terms to know… ► Magma- liquid rock ► Lava- magma that breaks through to the surface of the earth ► Vent- opening through which magma flows ► Volcano- structure formed by the vent and the volcanic material that builts ► Pyroclastic material- ash and rock material ejected from a volcano
Volcanoes
Where do volcanoes happen? ► Subduction zones- Pacific Ring of Fire ► Mid-Ocean Ridges- fissures (breaks and cracks, Iceland) ► Hot Spots- not along plate boundaries- areas of volcanic activity within the plate
Where?
What erupts? ► Lava ► Mafic- oceanic, slow ► Felsic- continents, fast ► Gases ► Rock fragments or Pyroclastic Material ► Volcanic Ash ► Volcanic Dust ► Volcanic Bombs (hot) and Blocks (cold)
3 Types of Volcanoes ► Shield Volcano ► Cinder Cone ► Composite Volcano
Shield Volcano ► Broad base ► Gentle sloping sides ► Covers a wide area ► Lava builds up slowly to form volcano body ► Quiet eruptions ► Hawaiian Islands
Cinder Cone ► Explosive eruptions ► Very steep sides (40 degrees or more) ► Solid fragments (pyroclastic material) that are ejected make the volcano body ► Rarely more than a few hundred meters high
Composite Volcano ► Both explosive and quiet eruptions ► Body of volcano made of alternating layers of lava (quiet eruptions) and pyroclastic material (explosive eruptions) ► Mt. St. Helens (USA) and Mt. Fuji (Japan)
The Ring of Fire ► Ring Of Fire IMAX movie ► Other Videos ► Volcano Concept Map ► Plotting the Ring of Fire