Question #4eb9a

1 Answer
Dec 27, 2017

Subduction zone and convergent plate boundary.


In the Cascade Range the Pacific plate is converging against the North America plate and, because the ocean crust is denser and heavier than the continental crust, it sinks below the latter.

When the pacific plate sinks deeper it is heated by the geothermal heat, plus the friction, and the rocks melt feeding the magmatic activity of the volcanoes of the Cascade Range.

The Japan is part of a volcanic arc where two oceanic plates, the Pacific plate and the Philippine Sea plate are subducted below the continental Eurasia plate.

In both settings extreme tensions are generated leading to the formation of sismogenic (active) faults that are the main source of earthquakes.