The Earth is an extremely dynamic planet. Watch as earthquakes take place in time sequence and note the passage of months and years at the bottom of the screen. Notice that earthquakes cluster in bands. These seismically active zones outline the boundaries of Earth's tectonic plates. The narrow band of earthquakes in the middle of the Atlantic Ocean marks a spreading ridge, where new material is added to the growing plates on either side. The Pacific Plate is ringed on most sides by subduction zones, where one plate descends beneath another, generating abundant and large earthquakes in the process.
