The continental sized plates are African, American, Antarctic, Indo-Australian, Eurasian and pacific plate. Apart from this, several smaller plates like Andaman, Philippine plate also exist. As plate glides over the asthenosphere, the continents and oceans move with it.  Because the plates move in different directions, they knock against their neighbors at boundaries. The great forces thus generated at plate boundary build mountain ranges, cause volcanic eruptions and earthquakes. Most of the Earth’s major geological activity occurs at plate boundaries, the zones where plates meet and interact. Figure 1.5 depicts the distribution of earthquake epicentres around the world.
The earthquake that occurs at a plate boundary is known as inter-plate earthquake. Not all earthquakes occur at plate boundaries. Though, interior portion of a plate is usually tectonically quiet, earthquakes also occur far from plate boundaries. These earthquakes are known as intra-plate earthquakes. The recurrence time for an intra-plate earthquake is much longer than that of inter-plate earthquakes