In 1815, the German geologist Leopold von Buch visited the Las Cañadas Caldera Teide, Tenerife, and the Caldera de Taburiente, La Palma, both in the Canary Islands. When he published his memoirs he introduced the term "caldera" into the geological vocabulary.
Caldera diagram |
If the magma is rich in silica, the caldera is often filled in with ignimbrite, tuff, rhyolite, and other igneous rocks. Silica-rich magma does have a high viscosity, and therefore does not flow easily like basalt. As a result, gases tend to become trapped at high pressure within the magma. When the magma approaches the surface of the Earth, the rapid off-loading of overlying material causes the trapped gases to decompress rapidly, thus triggering explosive destruction of the magma and spreading volcanic ash over wide areas. There is a type of lava in explosive calderas called A'a. Further lava flows may be erupted.
If volcanic activity continues the centre of the caldera may be uplifted in the form of a resurgent dome such as is seen at Cerro Galán, Lake Toba, Yellowstone, etc., by subsequent intrusion of magma. A silicic or rhyolitic caldera may erupt hundreds or even thousands of cubic kilometers of material in a single event. Even small caldera-forming eruptions, such as Krakatoa in 1883 or Mount Pinatubo in 1991, may result in significant local destruction and a noticeable drop in temperature around the world. Large calderas may have even greater effects.
When Yellowstone Caldera last erupted some 640,000 years ago, it released about 1,000 km3 of dense rock equivalent (DRE) material, covering a substantial part of North America in up to two metres of debris. By comparison, when Mount St. Helens erupted in 1980, it released ~1.2 km3 (DRE) of ejecta. The ecological effects of the eruption of a large caldera can be seen in the record of the Lake Toba eruption in Indonesia.
Mt.Aso's caldera measures 25 km north-south and 18 km east-west |
Mount Pinatubo, Philippines |
At some points in geological time, rhyolitic calderas have appeared in distinct clusters. The remnants of such clusters may be found in places such as the San Juan Mountains of Colorado (erupted during the Tertiary Period) or the Saint Francois Mountain Range of Missouri (erupted during the Proterozoic).
Crater Lake, Oregon, formed around 5,680 BC |
Pico de Fogo, a caldera volcano that lies in the island of Fogo |
Since the early 1960s it has been known that volcanism exists on other planets and moons. Through the use of manned and unmanned spacecraft, volcanism has been discovered on Venus, Mars, the Moon and Io, a satellite of Jupiter. None of these orbs has plate tectonics, which contributes approximately 60% of the Earth's volcanic activity (the other 40% attributed to hot spot volcanism) (Wilson 2008). Caldera structure is similar on all of these planetary bodies, though the size varies considerably.
Mount Pleasant Caldera, southwestern New Brunswick, Canada |
List of Volcanic Caldera
Africa
Ngorongoro Crater (Tanzania, Africa)
Menengai Crater (Kenya, Africa)
Mount Elgon (Uganda/Kenya)
Mount Fogo, Cape Verde
Erta Ale, Ethiopia
See Europe for calderas in the Canary Islands
Asia
Aira Caldera (Kagoshima Prefecture, Japan)
Aso (Kumamoto Prefecture, Japan)
Batur (Bali, Indonesia)
Mount Halla (Jeju-do, South Korea)
Kikai Caldera (Kagoshima Prefecture, Japan)
Krakatoa (Sunda Strait, Indonesia)
Mount Pinatubo (Luzon, Philippines)
Taal Volcano (Luzon, Philippines)
Lake Toba (Sumatra, Indonesia)
Mount Tambora (Sumbawa, Indonesia)
Tao-Rusyr Caldera (Onekotan, Russia)
Towada (Aomori Prefecture, Japan)
Tazawa (Akita Prefecture, Japan)
Ashi (Kanagawa Prefecture, Japan)
America
USA
Mount Aniakchak (Alaska, US)
Crater Lake on Mount Mazama (Crater Lake National Park, Oregon, US)
Mount Katmai (Alaska, US)
La Garita Caldera (Colorado, US)
Long Valley (California, US)
Henry's Fork Caldera (Idaho, US)
Island Park Caldera (Idaho, Wyoming, US)
Newberry Volcano (Oregon, US)
Mount Okmok (Alaska, US)
Valles Caldera (New Mexico, US)
Yellowstone Caldera (Wyoming, US)
Canada
Silverthrone Caldera (British Columbia, Canada)
Mount Edziza (British Columbia, Canada)
Bennett Lake Volcanic Complex (British Columbia/Yukon, Canada)
Mount Pleasant Caldera (New Brunswick, Canada)
Sturgeon Lake Caldera (Ontario, Canada)
Mount Skukum Volcanic Complex (Yukon, Canada)
Blake River Megacaldera Complex (Quebec/Ontario, Canada)
New Senator Caldera (Quebec, Canada)
Misema Caldera (Ontario/Quebec, Canada)
Noranda Caldera (Quebec, Canada)
Chile
Chaitén, Chile
Cordillera Nevada Caldera
Laguna del Maule, Chile
Sollipulli, Chile
Ecuador
Pululahua Geobotanical Reserve
Cuicocha
El Salvador
Lake Ilopango
Lake Coatepeque
Other
Masaya, Nicaragua
Lake Atitlan, Guatemala
Fernandina Island, Galapagos Islands, Ecuador
Galán, Argentina
Europe
Santorini (Greece)
Askja (Iceland)
Campi Flegrei (Italy)
Lake Bracciano (Italy)
Las Cañadas on Teide (Spain)
Ardnamurchan (Scotland)
Oceana
Lake Taupo (New Zealand)
Kilauea (Hawaii, US)
Moku‘āweoweo Caldera on Mauna Loa (Hawaii, US)
Rano Kau (Easter Island, Chile)