INSIDE EARTH: CHAPTER 3- VOLCANOES Section 1: Volcanoes and Plate Tectonics

What is a volcano? Volcano - weak spot in the crust where molten material, or magma, comes to the surface

Magma - molten mixture of rock, gasses, and water from the mantle What is a volcano? Magma - molten mixture of rock, gasses, and water from the mantle

Lava- magma that reaches the surface What is a volcano? Lava- magma that reaches the surface

Location of volcanoes There are about 600 active volcanoes on land. Many more lie below the sea.

Location of volcanoes Ring of Fire: a major volcanic belt formed by many volcanoes at the edge of the Pacific Ocean

Location of volcanoes Most volcanoes occur along diverging plate boundaries, such as the mid-ocean ridge or in subduction zones around the edges of oceans

Location of volcanoes Many volcanoes occur on islands, near boundaries where two plate collide.

Location of volcanoes The resulting volcanoes create a string of islands called an island arc.

Hot Spot Volcanoes Some volcanoes result from “hot spots” in Earth’s mantle. A hot spot is a weak spot where magma from deep in the mantle melts through the crust like a blow torch.

Hot Spot Volcanoes Hot spots often lie in the middle of continental or oceanic plates far away from plate boundaries.

Hot Spot Volcanoes Can gradually form a series of volcanic islands, for example the Hawaiian Islands.

Hot Spot Volcanoes The Hawaiian Islands formed over millions of years as the Pacific plate drifted over a hot spot.

Hot Spot Volcanoes They can also form under the continents. An example of this is Yellowstone National Park in Wyoming.

Hot Spot Volcanoes Yellowstone marks a major hot spot under the North American plate.