Which best describes a caldera?
A) a collapse pit less than 1 km2 on the summit of a volcano
B) a small, steep- sided, volcanic depression bored out by an eruptive plume
C) a large depression hundreds of km across full of volcanic deposits
D) a large circular volcanic depression caused by collapse after a large scale, explosive felsic eruption

Question

Quizplus · Accepted Answer

A caldera is a large, usually circular depression that forms following the evacuation of a magma chamber/reservoir. When a significant volume of magma is erupted over a short time, structural support for the rock above the magma chamber is lost, leading to collapse of the ground and formation of a large depression. This process often follows large-scale, explosive eruptions of felsic (silica-rich) magma.

Which Best Describes a Caldera