Have you ever seen a volcano up close and personal?  The rupture in the crust allows hot lava,ash, and gases to escape 
No only in pics or on tv but they are amazing
Volcano
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
Earth's volcanoes occur because its crust is broken into 17 major, rigid tectonic plates that float on a hotter, softer layer in its mantle. Therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging, and most are found underwater. For example, a mid-oceanic
around them.
On Earth, volcanoes are mainly of two types: shield volcanoes and composite or stratovolcanoes. The shield volcanoes, for example those in Hawaii, eject magma from the depths of the Earth in zones called "hot spots". The lava from these volcanos is relatively fluid and permits the escape of gases. Composite volcanos, such as Mount Saint Helens and Mount Pinatubo, are associated with tectonic plates. In this type of volcano, the oceanic crust of one plate is sliding underneath the other in a subduction