Definition: Caldera Depression
From Open Energy Information
Caldera Depression
Calderas form from the catastrophic eruption of large amounts of felsic lava and ash. Emptying of the magma chamber and subsequent collapse of the overlying volcanic edifice forms a ring-shaped caldera depression up to several kilometers in diameter. The edges of the underlying magma chamber are roughly marked by a ring fracture zone that acts as a conduit for ongoing volcanism and hydrothermal activity.