A caldera forms as a volcano's magma chamber empties, resulting in a loss of support for the earth above it. These bowl-shaped depressions can range in size from a few hundred meters to several kilometers wide. They are generally caused by large volcanic eruptions.Know More
Calderas and craters are not to be confused. Craters are created by an explosion of rock upward from a volcanic blast. Calderas are created by a sinking of the earth into the empty magma chamber left behind after the eruption.
The intense pressure of trapped gases in the magma chamber bulges the earth above and creates vents and cracks in the land. Once this pressure is released, the earth collapses back into the now empty space from which the pressure appeared. Sometimes the land collapses irregularly, leaving behind an uneven depression.
Eruptions large enough to create calderas have not occurred during recorded human history. However, geologic evidence indicates massive eruptions in Earth's past creating calderas such as the one found in Yellowstone National Park. The Yellowstone Caldera lies above a magma chamber 24 to 48 miles wide. The last eruption of this magma chamber occurred approximately 640,000 years ago and was 1,000 times larger than the eruption of Mt. Saint Helens.Learn more about Volcanoes
A volcano forms when a vent in the Earth's crust allows magma to well up from below. The magma fills a void underneath the surface, and when it builds up enough pressure, it bursts through to the surface. As the magma cools, it hardens into rock, and multiple eruptions may build up the mountainous form of a volcano.Full Answer >
Krakatoa, or Krakatau, is a caldera volcano. Calderas are depressions formed when a volcano collapses into itself. The result is a large crater surrounded by steep cliffs and possibly filled with lakes.Full Answer >
The El Chichón volcano in Mexico is a caldera volcano with an elevation of 3,772 feet. This caldera is a result of a series of eruptions in 1982.Full Answer >
When a volcano erupts, magma from beneath the Earth is forced out of the volcano's mouth in the form of molten lava. Large amounts of gases and ash can also be released with the lava, depending on the type of eruption.Full Answer >