Radioactive decay in the Earth's dynamic interior drives a process of mantle convection that causes the rigid plates of the solid outer crust to migrate. Subduction zones occur where plates are driven under other crustal material and consumed back into the mantle. Mountain zones, island arcs, and foretroughs are associated with such areas, and earthquakes can be common. For example, in the foretrough in front of the Himalayan Mountains (in India and Bangladesh), many high-magnitude earthquakes have occurred. Seismicity is associated with consumption of the crust, orogeny (mountain building), and downwarping (gentle bending of the crust) in front of the mountain chains.

Earthquakes occur more rarely at the trailing margins of plates, and tend to be less strong where crust is being created. However, there are ...