About Yellowstone Caldera
The Yellowstone Caldera is the volcanic caldera in Yellowstone National Park in the United States. The caldera is located in the northwest corner of Wyoming, in which the vast majority of the park is contained. The major features of the caldera measure about 55 kilometers (34 mi) by 72 kilometers (45 mi) as determined by geological field work conducted by Bob Christiansen of the United States Geological Survey in the 1960s and 1970s. After a BBC television science program coined the term supervolcano in 2000, it has often been referred to as the Yellowstone Supervolcano. Yellowstone, like Hawaii, is believed to lie on top of an area called a hotspot where light, hot, molten mantle rock rises towards the surface. While the Yellowstone hotspot is now under the Yellowstone Plateau, it previously helped create the eastern Snake River Plain (to the west of Yellowstone) through a series of huge volcanic eruptions. Although the hotspot's apparent motion is to the east-northeast, the North American Plate is really moving west-southwest over the stationary hotspot deep underneath.
Over the past 17 million years or so, this hotspot has generated a succession of violent eruptions and less violent floods of basaltic lava. Together these eruptions have helped create the eastern part of the Snake River Plain from a once-mountainous region. At least a dozen or so of these eruptions were so massive that they are classified as supereruptions. Volcanic eruptions sometimes empty their stores of magma so swiftly that they cause the overlying land to collapse into the emptied magma chamber, forming a geographic depression called a caldera. Calderas formed from explosive supereruptions can be as wide and deep as mid- to large-sized lakes and can be responsible for destroying broad swaths of mountain ranges.
The oldest identified caldera remnant straddles the border near McDermitt, Nevada-Oregon. Progressively younger caldera remnants, most grouped in several overlapping volcanic fields, extend from the Nevada-Oregon border through the eastern Snake River Plain and terminate in the Yellowstone Plateau. One such caldera, the Bruneau-Jarbidge caldera in southern Idaho, was formed between 10 and 12 million years ago, and the event dropped ash to the depth of a foot 1,000 miles (1,600 km) away in northeastern Nebraska and killed a large herd of rhinoceroses, camels, and other animals at Ashfall Fossil Beds State Historical Park. Within the past 17 million years, 142 or more caldera-forming eruptions have occurred from the Yellowstone hotspot . The loosely defined term 'supervolcano' has been used to describe volcanic fields that produce exceptionally large volcanic eruptions. Thus defined, the Yellowstone Supervolcano is the volcanic field which produced the latest three supereruptions from the Yellowstone hotspot. The three super eruptions occurred 2.1 million, 1.3 million, and 640,000 years ago; forming the Island Park Caldera, the Henry's Fork Caldera, and Yellowstone calderas, respectively. The Island Park Caldera supereruption (2.1 million years ago), which produced the Huckleberry Ridge Tuff, was the largest and produced 2,500 times as much ash as the 1980 Mount St. Helens eruption. The next biggest supereruption formed the Yellowstone Caldera (630,000 years ago) and produced the Lava Creek Tuff. The Henry's Fork Caldera (1.2 million years ago) produced the smaller Mesa Falls Tuff but is the only caldera from the SRP-Y hotspot that is plainly visible today.
Non-explosive eruptions of lava and less-violent explosive eruptions have occurred in and near the Yellowstone caldera since the last supereruption. The most recent lava flow occurred about 70,000 years ago, while the largest violent eruption excavated the West Thumb of Lake Yellowstone around 150,000 years ago. Smaller steam explosions occur as well; an explosion 13,800 years ago left a 5 kilometer diameter crater at Mary Bay on the edge of Yellowstone Lake (located in the center of the caldera). Currently, volcanic activity is exhibited via numerous geothermal vents scattered throughout the region, including the famous Old Faithful Geyser, plus recorded ground swelling indicating ongoing inflation of the underlying magma chamber.
The volcanic eruptions, as well as the continuing geothermal activity, are a result of a great cove of magma located below the caldera's surface. The magma in this cove contains gases that are kept dissolved only by the immense pressure that the magma is under. If the pressure is released to a sufficient degree by some geological shift, then some of the gases bubble out and cause the magma to expand. This can cause a runaway reaction. If the expansion results in further relief of pressure, for example, by blowing crust material off the top of the chamber, the result is a very big gas explosion.
Learn more about Super Volcanoes: Interactive - Hotspot Yellowstonehttp://dsc.discovery.com/convergence/supervolcano/supervolcano.html Yellowstone Monitor: http://www.isthisthingon.org/Yellowstone/daythumbs.php reference this page to see the stations on a park map background Monitoring Earthquakes in Yellowstone National Parkhttp://volcanoes.usgs.gov/yvo/activity/monitoring/earthquakes.php Earthquake List for Map Yellowstonehttp://earthquake.usgs.gov/earthquakes/recenteqsus/Maps/special/Yellowstone_eqs.php Recent Earthquakes in the Intermountain West http://www.seis.utah.edu/req2webdir/recenteqs/Maps/Yellowstone.html
Recent quakes in Yellowstone: http://earthquake.usgs.gov/eqcenter/recenteqsus/Maps/US2/43.45.-111.-109_eqs.php Yellowstone Watch Webcams: New Yellowstone Webcams (all) http://www.nps.gov/yell/photosmultimedia/webcams.htm Mammoth Cam http://www.nps.gov/yell/mammothcam.htm Old Faithful http://www.nps.gov/yell/oldfaithfulcam.htm Watch the Geysers http://www.geyserstudy.org/geyser_main.htm Yellowstone North WebCam#2 http://www.yellowstone-natl-park.com/northcam.htm The Yellowstone Seismic Network (YSN) is operated cooperatively by University of Utah, the US Geological Survey's Volcano Hazards Program, and the National Park Service. The network covers the seismically and volcanically active Yellowstone National Park and surrounding area. It is designed for the purpose of monitoring volcano and geyser-related earthquake activity and for studying the subsurface processes of Yellowstone.
Monitoring Earthquakes in Yellowstone National Park Earthquake Data (from the University of Utah)
- Recent earthquake activity in Yellowstone National Park (map and catalog with links).
- Recent earthquake activity in the Intermountain West (map and catalog with links).
- Live seismograms for the Yellowstone area (links to webicorders, updated every ten minutes).
- Animations of recent earthquakes (shows earthquake activity over the past seven days).
- Earthquake Catalog of Yellowstone area (maps and catalog).
- Discussion of earthquakes in Yellowstone area (map and discussion). Background Information