1. 8.1 Notes Where Volcanoes Form

2. What are volcanoes? What are volcanoes? Volcanoes - locations where hot magma pushes up on Earth’s surface Volcanoes - locations where hot magma pushes up on Earth’s surface –mountains with magma pushing up

3. Where are volcanoes located? Where are volcanoes located? Mostly on plate boundaries Mostly on plate boundaries

4. What is the “Ring of Fire”? What is the “Ring of Fire”? A chain of volcanoes boarding the Pacific Ocean. A chain of volcanoes boarding the Pacific Ocean.

5. 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? movement of the tectonic plates movement of the tectonic plates What is magma? What is magma? melted rock melted rock

6. 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.

7. Mt. St. Helens, Washington erupted in 1980

8. Mt. St. Helens, Washington 1982

9. How can volcanoes form at divergent boundaries? How can volcanoes form at divergent boundaries? The plates float on the asthenosphere, which contains magma. So, when the plates pull apart, at a divergent boundary, magma comes up through the crust forming volcanoes. This is what creates mid-ocean ridges. The plates float on the asthenosphere, which contains magma. So, when the plates pull apart, at a divergent boundary, magma comes up through the crust forming volcanoes. This is what creates mid-ocean ridges. Another name for a deep set of cracks is a rift zone Another name for a deep set of cracks is a rift zone Most of the time this happens underwater (in the ocean). However, there are a couple of exceptions. Iceland is being pulled apart by a mid-ocean ridge and is above sea-level. Most of the time this happens underwater (in the ocean). However, there are a couple of exceptions. Iceland is being pulled apart by a mid-ocean ridge and is above sea-level.

10. How can volcanoes form at convergent boundaries? How can volcanoes form at convergent boundaries? When an oceanic crust collides with a continental crust, the ocean crust sinks beneath it because it is denser (heavier). The continental crust goes up forming a mountain because it is less dense than oceanic crust. As the oceanic crust sinks, it is burned back into magma because of the heat from the asthenosphere (magma). Sometimes due to the immense pressure the magma will rise up under the mountain forming a volcano. When an oceanic crust collides with a continental crust, the ocean crust sinks beneath it because it is denser (heavier). The continental crust goes up forming a mountain because it is less dense than oceanic crust. As the oceanic crust sinks, it is burned back into magma because of the heat from the asthenosphere (magma). Sometimes due to the immense pressure the magma will rise up under the mountain forming a volcano.

11. Volcanoes @ Convergent Boundaries

12. What is a hot spot? What is a hot spot? A volcanically active spot on a plate that is no where near a plate boundary. A volcanically active spot on a plate that is no where near a plate boundary. Why would there be a volcano no where near a plate boundary? Why would there be a volcano no where near a plate boundary? The plate may be weak or think in that spot, so the magma can break through easily. The plate may be weak or think in that spot, so the magma can break through easily.

13. How was Hawaii formed? How was Hawaii formed? Hawaii is over a hot spot. Hawaii is over a hot spot. How many Hawaiian islands are there today? Were there less in the past? Will there be more in the future? How many Hawaiian islands are there today? Were there less in the past? Will there be more in the future? 8 Yes Yes Yes – the pacific plate is moving and the hot spot does not, so more islands are growing under water Yes – the pacific plate is moving and the hot spot does not, so more islands are growing under water

14. Hawaii – A hot spot

15. Which island is the Hawaiian hot spot located under right now? Which island is the Hawaiian hot spot located under right now? The big island – where the most active volcanoes are The big island – where the most active volcanoes are

16. Pakistan’s NEW Island On September 24, 2013 a 7.7 magnitude killed 350 people and left 100,000 homeless