A volcanic crater can be of large dimensions, and sometimes of great depth.
In most volcanoes, the crater is situated at the top of a mountain formed from the erupted volcanic deposits such as lava flows and tephra.
[3] A crater may be breached during an eruption, either by explosions or by lava, or through later erosion.
These volcanic explosion craters are formed when magma rises through water-saturated rocks, which causes a phreatic eruption.
Volcanic craters from phreatic eruptions often occur on plains away from other obvious volcanoes.