Plates can collide to build mountains in different
ways. They can create trenches and island arcs when oceanic crust and
oceanic crust "bump" into each other. This creates volcanoes
and earthquakes. An example of this type of collision is the Japanese
Islands in the western Pacific Ocean. You can also have oceanic crust
collide with continental crust, like you have along northern California
to Washington coastline. This creates trenches and volcanic mountains.
Earthquakes are common in this type of collision. Continental crust that
bumps into another continental crust produces very large mountain
ranges, like in the Himalaya Mountains on the southern Asian continent.
This produces earthquakes but no volcanoes.