is a collapse feature typically found on the summits of large volcanoes.
Calderas form when magma is removed from deep within a volcano due to
a large eruption or intrusion. When the magma is suddenly removed the
summit of the volcano becomes partially unsupported. The part of the volcano
above the magma chamber then collapses downward, sliding along curved
faults that bound the collapse region. At Axial Volcano, the caldera walls
are up to 100 m high. The magma reservoir beneath Axial lies about 2-4
km below the summit. It is not clear whether Axial's caldera was caused
by a sudden collapse during a particularly large eruption or by a series
of smaller events over a longer period of time.