If the magma chamber beneath an erupting volcano empties and then collapses, what kind of feature will form? explain

A caldera will form; collapse calderas are formed when the now unsupported rock that forms the roof of the magma chamber beneath the volcano collapses and forms a large crater.

Sequoia national park  /  inyo national forest, california, u.s. mount whitney is the tallest mountain in california, as well as the highest summit in the contiguous united states and thesierra nevada—with an elevation of 14,505 feet (4,421 m).