Volcanoes are not found in all parts of the world because volcanoes need certain subsurface conditions to take birth and become/remain active. These conditions exist where there is high level of activities below ground (crust). read more
The fist two are shield volcanoes; the latter is called a polygenetic volcano: the bottom half of Mt. Erebus was a shield volcano, but the upper, newer portion is a stratocone. It is currently erupting and the only one of it’s kind with a unique form of lava. read more
Volcanoes are usually found at the edges of tectonic plates, or in other parts of the world where the crust of the earth has a really weak spot. Volcanoes are found where lava naturally flows and just like water or electricity, lava takes the path of least resistance. read more