In the example to the right, an oceanic plate is colliding with a continental plate. Note that the more dense oceanic plate is being pulled down or subducted beneath the continental plate. This causes earthquakes deep in the earth as the two plates rub up against each other.
Volcanoes form as magma rises from the melted slab.
The deep sea floor trench marks the area of subduction. If you look at the convergent boundaries of the world, you will see that both earthquake and volcanic activity may occur there. For example, India is convergent to Asia. This means that India is converging on or colliding with Asia at Tibet and the Himalaya Mountains. Because India, which belongs to the Indo-Australian plate, is moving northward, it is causing the Himalaya Mountains to build up to greater elevations.