Dormant volcano crater. Extinct volcanoes are no longer has a lava supply. 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. A volcanic crater is a roughly circular depression in the ground caused by volcanic activity. During volcanic eruptions, molten magma and volcanic gases rise from an underground magma chamber, through a tube-shaped conduit, until they reach the crater’s vent, from where the gases escape into the atmosphere and the magma is erupted as lava. A volcanic crater can be of large dimensions, and sometimes of great depth. During certain types of explosive eruptions, a volcano’s magma chamber may empty enough for an area above it to subside, forming a type of larger depression known as a caldera. Dormant volcanos. 4K UHD 3840×2160 30p.