5.1 Volcanoes

volcano - a mountain that forms in Earth’s crust when molten material, or magma, reaches the surface volcano - a mountain that forms in Earth’s crust when molten material, or magma, reaches the surface magma – a molten mixture of rock-forming substances, gases, and water from the mantle / asthenosphere magma – a molten mixture of rock-forming substances, gases, and water from the mantle / asthenosphere lava – when magma reaches the surface lava – when magma reaches the surface

Ring of Fire – many volcanoes in one major belt around the Pacific Ocean

Ring of Fire – Pacific Ocean North America South America Pacific Ocean Asia Australia

What is a volcanic eruption? What is a volcanic eruption? when magma is pushing up through the cracks of the crust when magma is pushing up through the cracks of the crust What causes a volcanic eruption? What causes a volcanic eruption? pressure pressure

What happens to the habitat (environment) immediately after an eruption? What happens to the habitat (environment) immediately after an eruption? It is destroyed. It dies. It is burnt. It is destroyed. It dies. It is burnt. What happens to the habitat 2-3 years after an eruption? What happens to the habitat 2-3 years after an eruption? It regrows. It regrows.

Mt. St. Helens, Washington erupted in 1980

Mt. St. Helens, Washington 1982

How and where are volcanoes created? How and where are volcanoes created? At subduction zones where magma is pushed up to the surface At subduction zones where magma is pushed up to the surface At divergent boundaries where magma is pushed up causing sea-floor spreading At divergent boundaries where magma is pushed up causing sea-floor spreading At hot spots where magma randomly comes up in the middle of a plate (Hawaii) At hot spots where magma randomly comes up in the middle of a plate (Hawaii) “Ring of Fire” – located along the pacific ocean has the most volcanoes in the world “Ring of Fire” – located along the pacific ocean has the most volcanoes in the world

island arc – a string of island created due to plate movement island arc – a string of island created due to plate movement hot spot – an area where molten material rises up through the crust no where near a plate boundary hot spot – an area where molten material rises up through the crust no where near a plate boundary

Hawaii is an island arc under a hot spot.