: "One of the most eye-catching guides to the world’s volcanoes ever published.
: Our professional team of volcanologists and photographers offers unique travel opportunities: volcano expeditions, photo tours, and relaxed walking & study tours.
Volcano Calendar 2016
: We're proud to present our new volcano calendar 2016: 13 different and attractive images of volcanoes, volcanic landscapes and phenomena taken during volcano tours over the past few years.
Maintaining the volcano and earthquake news sections on this website, the free Volcano Webcams tool
and interactive map widget
is a free-time, both time- and server cost intensive effort.
If you find the information useful and would like to support us, and help keep it alive and improve it, please consider making a small donation
. Thank you!
Illustrated Volcano Glossary
Large crater, usually several kilometers across, formed by the collapse of the roof of a magma chamber emptied by large explosive eruptions.
A caldera is a large, usually circular depression at the summit of a volcano formed when magma is withdrawn or erupted from a shallow underground magma reservoir. The removal of large volumes of magma may result in loss of structural support for the overlying rock, thereby leading to collapse of the ground and formation of a large depression. Calderas are different from craters, which are smaller, circular depressions created primarily by explosive excavation of rock during eruptions. (From USGS Photoglossary).
Actually, calderas are a very common feature with most larger volcanoes. During the lifetime of a typical volcano, larger caldera-forming eruptions (that typically discharge around 1 km3 of magma or more) tend to ocur at typical time intervals of a few 1000 years. Subsequent smaller eruptions often rebuid the cone of the volcano, so that earlier calderas often are not easily visible.
Famous calderas include Santorini in Greece, the Campi Flegrei caldera, Italy, Crater Lake caldera in Oregon (USA), Yellowstone Caldera, Wyoming (USA), Long Valley Caldera in east California (USA), Batur, Tengger and Krakatoa volcanoes (Indonesia) and many more.
-- The largest eruption of the 20th century from the Novarupta vent in the Valley of 10,000 Smokes of Alaska, ejected about 12 km3 of magma and resulted in the formation of a caldera 3 km across. Amazingly, the caldera collapse didn't occur at the eruption vent, but 10 km away at Katmai, a stratovolcano! Apparently magma drained away from Katmai's magma reservoir to Novarupta's erupting vent.
-- Yellowstone National Park consists of three enormous calderas that erupted about 2, 1.2, and 0.6 million years ago. The most recent caldera is 45 km across and 75 km long!
-- Caldera-forming eruptions are the largest eruptions on Earth. For example, the Fish Canyon eruption in southwestern Colorado (United States) about 28 million years ago erupted more than 5,000 km3 of magma from La Garita caldera. That's enough magma to bury the entire state of California to a depth of nearly 12 m!
(from: USGS Photoglossary)
Related keywords (2): crater
More on VolcanoDiscovery:
One of the world's most famous volcanoes looming over the City of Naples
Introduction to Plate Tectonics
: The Earth's upper, rigid layer is broken into several plates which are in constant motion to one another. Most earthquakes and volcanoes occur as result of these plate boundaries.