The movement of tectonic plates causes various geological phenomena including volcanoes, mountains, and earthquakes. There are three types of plate boundaries - divergent where plates move apart, convergent where they collide in subduction or collision zones, and transform where they slide past each other. Earthquakes occur when stress builds up at faults until the plates suddenly slip, releasing energy. Large earthquakes can generate tsunamis through displacement of water. Volcanoes form at plate boundaries as magma rises from below the crust.

1. Internal ForcesShaping the Earth

4. Convergent boundary: the plates collide (2 types) Subduction: the plates collide and one plate is forced under the other. Often, the plate that is forced under will melt when it gets deep and hot enough and the resulting magma forces its way back to the surface as a volcano.

6. Collision: The plates collide and buckle and fold. Mountains may result. Take India, for example. Remember this? That’s India. Note that it’s on its own tectonic plate Millions of years ago, the thing rampaged north and crashed into Asia. It created the Himalaya Mountains, including Mt. Everest. Even today, the mountains are still growing by a few millimeters per year. They’ve also found ancient ocean fossils in these, the highest points on Earth.

12. Normally (hopefully), the plates slide past each other steadily and gradually and we don’t notice it.

13. Sometimes, though, the crust at the fault sticks, but the plates keep moving. This builds up tremendous pressure on the stuck crusts until they finally unstick and they suddenly move a lot at once. This is when the earthquake happens.

19. This shows the progression of the 2004 tsunami

20. Tsunami 1 Tsunami 2

31. The Empire State Building is 1,250 feet tall.

36. Sometimes it’s a gradual flow. Other times, it erupts in a violent explosion, sometimes releasing more energy than nuclear weapons.