1. Earthquakes, Volcanoes, and Mountain Building

2. Tectonic Plate Boundaries Convergent: Tectonic plates collide Divergent: Tectonic plates move away from one another Transform: Tectonic plates slide past each other horizontally

3. Mountain Building Mountains are landmasses that rise well above Earth’s surface. Mountains form at convergent boundaries. –Two continental plates of equal densities collide and push up the land Earth’s crust folds and breaks as a result

4. Earthquakes Earthquakes are the shaking movement of Earth’s surface. Earthquakes occur at transform boundaries. –The boundaries of two plates move against each other –Pressure is built up, causing a violent shift This movement causes an earthquake.

5. Volcanoes Volcanoes are mountains that form when magma is forced to Earth’s surface Volcanoes form at convergent boundaries, divergent boundaries, and hot spots.

6. Volcanoes at Convergent Boundaries When two plates collide, the denser one subducts beneath the less dense one. –The denser plate that goes under melts and forms magma This magma can be forced through vents to form volcanic mountains.

7. Volcanoes at Convergent Boundaries Example: Mount Etna, Ring of Fire volcanoes

8. Volcanoes at Divergent Boundaries Two plates beneath the ocean can move apart –A vent is exposed and magma slowly rises to the surface New oceanic lithosphere is formed This process is called sea-floor spreading

9. Volcanoes at Divergent Boundaries Example: Iceland’s volcanic islands

10. Volcanoes at Hot Spots A hot spot is a place beneath the earth where very hot magma exists. –When a plate moves over a hot spot in the mantle, a vent can be exposed Fountains of magma punch through the crust

11. Volcanoes at Hot Spots Example: The Hawaiian Islands