Why are earthquakes and volcanoes located near plate boundaries?

Answer 1

Its the nature of their formation.

1) Most volcanoes are located there because as an oceanic plate gets pushed down (it is a more dense plate) it dives into the mantle, it begins to melt and pressure forces its way to the surface.

2) Earthquakes are located mainly around plate boundaries because as plates slide/collide past/into/away from each other the ground moves. When plates collide, they push into each other and "crunch up" causing seismic activity. When they slide past each other, they "rub" against each other and cause seismic activity. When they move away from each other, molten magma rises to the surface to fill the void causing displacement and seismic activity.

And thats it in a very basic nutshell.

Answer 2

AS ONE PLATE IS SUBDUCTED BENEATH ANOTHER IT CAUSES CRACKS AND FISSURES TO FORM ALLOWING MAGMA OR LAVA TO SEEP UPWARD AND FORM A VOLCANO WHEN IT REACHES THE SURFACE.