Tectonic plate boundaries are divided into three major groups: convergent, divergent, and transform-fault boundaries. Convergent boundaries occur where two tectonic plates are moving closer together, which can cause one of two possible outcomes. In a subduction situation, one plate is driven downward into the mantle beneath the other. In a collision situation, the plates push one another upward, creating mountain ranges such as the Himalayas. Both of these types of convergent boundary can create powerful earthquake zones, as well as volcanoes in the subduction situation.
Divergent boundaries occur where the plates are moving away from each other. Magma from beneath the Earth's crust wells up into the gap created between the plates, so there may be lava flows, but usually there is not enough pressure to create earthquakes. Hence divergent boundaries have the fewest recorded damaging earthquakes.
Transform-fault boundaries happen where two plates are sliding past one another horizontally, and are associated with frequent earthquakes, some of considerable power.