Question: @Kate, Where are the most active volcanoes in the world?

Kate Dobson answered on 12 Nov 2014:

Most volcanoes are along the edges of the tectonic plates, Most of the major (and most explosive) volcanoes lie along destructive plate boundaries where one tectonic plate is pushed down into the mantle beneath another. The other place where you find lots of smaller volcanoes is under the ocean along the mid ocean ridges. These ocean ridges are the constructive plate boundaries where new crust is being formed all the time, and so are essentially just a string of volcanoes.

Here is a map: http://earth.rice.edu/mtpe/geo/geosphere/hot/volcanoes/volcanoes_b2.html