The three types of pf plate boundaries are spreading zones, transform faults and subduction zones. Most earthquakes occur along the boundaries of plate tectonics due to the effects of the earth's mantle layer that acts as a recycling agent and recycles 99% of the earth's surface layers from above.
Various tectonic forces and process act son these slabs and rocks from above and hence through the activities of erosion and denudation of the rocky masses these plates collide with each other as the earth is it's self not static its dynamic and moves continuously on a regular basis and hence changes take place on the surface of earth.
Thus it can be seen that the earthquakes and volcanic events occur at the plate boundaries and hence produce or are responsible for the various activities.
