Yellowstone Caldera

The Yellowstone Caldera is a volcanic caldera and supervolcano in Yellowstone National Park in the Western United States, sometimes referred to as the Yellowstone Supervolcano. The caldera and most of the park are located in the northwest corner of Wyoming. The major features of the caldera measure about 34 by 45 miles (55 by 72 km).[4]

The caldera formed during the last of three supereruptions over the past 2.1 million years: the Huckleberry Ridge eruption 2.1 million years ago (which created the Island Park Caldera and the Huckleberry Ridge Tuff); the Mesa Falls eruption 1.3 million years ago (which created the Henry's Fork Caldera and the Mesa Falls Tuff); and the Lava Creek eruption approximately 630,000 years ago (which created the Yellowstone Caldera and the Lava Creek Tuff).[5]

Yellowstone Caldera
Yellowstone River in Hayden Valley
The northeastern part of Yellowstone Caldera, with the Yellowstone River flowing through Hayden Valley and the caldera rim in the distance
Highest point
Elevation9,203[1] ft (2,805 m)
Coordinates44°24′N 110°42′W / 44.400°N 110.700°WCoordinates: 44°24′N 110°42′W / 44.400°N 110.700°W
LocationYellowstone National Park, Wyoming, United States
Parent rangeRocky Mountains
Topo mapUSGS Yellowstone National Park
Age of rock2,100,000–70,000 years[3]
Mountain typeCaldera[2] and supervolcano
Easiest routeHike/auto/bus

Volcanism at Yellowstone

Yellowstone Caldera map2
Yellowstone sits on top of four overlapping calderas. (US NPS)

Volcanism at Yellowstone is relatively recent, with calderas that were created during large eruptions that took place 2.1 million, 1.3 million, and 630,000 years ago. The calderas lie over a hotspot under the Yellowstone Plateau where light and hot magma (molten rock) from the mantle rises toward the surface. The hotspot appears to move across terrain in the east-northeast direction, but in fact the hotspot is much deeper than terrain and remains stationary while the North American Plate moves west-southwest over it.[6]

Over the past 18 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 (to the west of Yellowstone) from a once-mountainous region. At least a dozen of these eruptions were so massive that they are classified as supereruptions. Volcanic eruptions sometimes empty their stores of magma so swiftly that the overlying land collapses into the emptied magma chamber, forming a geographic depression called a caldera.

The oldest identified caldera remnant straddles the border near McDermitt, Nevada–Oregon, although there are volcaniclastic piles and arcuate faults that define caldera complexes more than 60 km (37 mi) in diameter in the Carmacks Group of southwest-central Yukon, Canada, which are interpreted to have been formed 70 million years ago by the Yellowstone hotspot.[7][8] Progressively younger caldera remnants, most grouped in several overlapping volcanic fields, extend from the NevadaOregon 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 a depth of one foot (30 cm) 1,000 miles (1,600 km) away in northeastern Nebraska and killed large herds of rhinoceros, camel, and other animals at Ashfall Fossil Beds State Historical Park. The United States Geological Survey ("USGS") estimates there are one or two major caldera-forming eruptions and 100 or so lava extruding eruptions per million years, and "several to many" steam eruptions per century.[9]

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; it also produced one additional smaller eruption, thereby creating the West Thumb of Yellowstone Lake[10] 174,000 years ago. The three supereruptions occurred 2.1 million, 1.3 million, and approximately 630,000 years ago, forming the Island Park Caldera, the Henry's Fork Caldera, and Yellowstone calderas, respectively.[11] 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 Snake River Plain-Yellowstone hotspot that is plainly visible today.[12]

Non-explosive eruptions of lava and less-violent explosive eruptions have occurred in and near the Yellowstone caldera since the last supereruption.[13][14] The most recent lava flow occurred about 70,000 years ago, while a 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 km (3.1 mi) diameter crater at Mary Bay on the edge of Yellowstone Lake (located in the center of the caldera).[15][3] 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 by the immense pressure under which the magma is contained. 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 chain 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 large gas explosion.

According to analysis of earthquake data in 2013, the magma chamber is 80 km (50 mi) long and 20 km (12 mi) wide. It also has 4,000 km3 (960 cu mi) underground volume, of which 6–8% is filled with molten rock. This is about 2.5 times bigger than scientists had previously imagined it to be; however, scientists believe that the proportion of molten rock in the chamber is much too low to allow another supereruption.[16][17]

Yellowstone hotspot origin

The source of the Yellowstone hotspot is controversial. Some geoscientists hypothesize that the Yellowstone hotspot is the effect of an interaction between local conditions in the lithosphere and upper mantle convection.[18][19] Others suggest an origin in the deep mantle (mantle plume).[20] Part of the controversy is the relatively sudden appearance of the hotspot in the geologic record. Additionally, the Columbia Basalt flows appeared at the same approximate time in the same place, causing speculation about their common origin. As the Yellowstone hotspot traveled to the east and north, the Columbia disturbance moved northward and eventually subsided.[21]

An alternate theory to the mantle plume model was proposed in 2018. It is suggested that the volcanism may be caused by upwellings from the lower mantle resulting from water-rich fragments of the Farallon Plate descending from the Cascadia subduction region, sheared off at a subducted spreading rift.[22]



Yellowstone earthquakes history
Number of earthquakes in Yellowstone National Park region (1973–2014) [23]

Volcanic and tectonic actions in the region cause between 1,000 and 2,000 measurable earthquakes annually. Most are relatively minor, measuring a magnitude of 3 or weaker. Occasionally, numerous earthquakes are detected in a relatively short period of time, an event known as an earthquake swarm. In 1985, more than 3,000 earthquakes were measured over a period of several months. More than 70 smaller swarms were detected between 1983 and 2008. The USGS states these swarms are likely caused by slips on pre-existing faults rather than by movements of magma or hydrothermal fluids.[24][25]

In December 2008, continuing into January 2009, more than 500 quakes were detected under the northwest end of Yellowstone Lake over a seven-day span, with the largest registering a magnitude of 3.9.[26][27] Another swarm started in January 2010, after the Haiti earthquake and before the Chile earthquake. With 1,620 small earthquakes between January 17, 2010, and February 1, 2010, this swarm was the second-largest ever recorded in the Yellowstone Caldera. The largest of these shocks was a magnitude 3.8 that occurred on January 21, 2010.[25][28] This swarm reached the background levels by February 21. On March 30, 2014, at 6:34 AM MST, a magnitude 4.8 earthquake struck Yellowstone, the largest recorded there since February 1980.[29] In February 2018, more than 300 earthquakes occurred, with the largest being a magnitude 2.9.[30]


Yellowstone Caldera
Diagram of the Yellowstone Caldera

The last full-scale eruption of the Yellowstone Supervolcano, the Lava Creek eruption which happened approximately 640,000 years ago,[31] ejected approximately 240 cubic miles (1,000 km3) of rock, dust and volcanic ash into the sky.[3]

Geologists are closely monitoring the rise and fall of the Yellowstone Plateau, which has been rising as quickly as 0.6 inches (1.5 cm) per year, as an indication of changes in magma chamber pressure.[32][33]

The upward movement of the Yellowstone caldera floor between 2004 and 2008—almost 3 inches (7.6 cm) each year—was more than three times greater than ever observed since such measurements began in 1923.[34] From 2004 to 2008, the land surface within the caldera moved upward as much as 8 inches (20 cm) at the White Lake GPS station.[35][36] By the end of 2009, the uplift had slowed significantly and appeared to have stopped.[37] In January 2010, the USGS stated that "uplift of the Yellowstone Caldera has slowed significantly"[38] and that uplift continues but at a slower pace.[39] The U.S. Geological Survey, University of Utah and National Park Service scientists with the Yellowstone Volcano Observatory maintain that they "see no evidence that another such cataclysmic eruption will occur at Yellowstone in the foreseeable future. Recurrence intervals of these events are neither regular nor predictable."[3] This conclusion was reiterated in December 2013 in the aftermath of the publication of a study by University of Utah scientists finding that the "size of the magma body beneath Yellowstone is significantly larger than had been thought". The Yellowstone Volcano Observatory issued a statement on its website stating,

Although fascinating, the new findings do not imply increased geologic hazards at Yellowstone, and certainly do not increase the chances of a 'supereruption' in the near future. Contrary to some media reports, Yellowstone is not 'overdue' for a supereruption.[40]

Other media reports were more hyperbolic in their coverage.[41]

A study published in GSA Today, the monthly news and science magazine of the Geological Society of America, identified three fault zones on which future eruptions are most likely to be centered.[42] Two of those areas are associated with lava flows aged 174,000–70,000 years, and the third is a focus of present-day seismicity.[42]

In 2017, NASA conducted a study to determine the feasibility of preventing the volcano from erupting. The results suggested that cooling the magma chamber by 35 percent would be enough to forestall such an incident. NASA proposed introducing water at high pressure 10 kilometers underground. The circulating water would release heat at the surface, possibly in a way that could be used as a power source. If enacted, the plan would cost about $3.46 billion. Nevertheless, according to Brian Wilson of the Jet Propulsion Laboratory, a completed project might trigger, instead of prevent, an eruption.[43][44]

Hydrothermal explosions

HotspotsSRP update2013
Path of the Yellowstone hot spot over the past 16 million years

Studies and analysis may indicate that the greater hazard comes from hydrothermal activity which occurs independently of volcanic activity. Over 20 large craters have been produced in the past 14,000 years, resulting in such features as Mary Bay, Turbid Lake, and Indian Pond which was created in an eruption about 1300 BC.

In a 2003 report, USGS researchers proposed that an earthquake may have displaced more than 77 million cubic feet (2,200,000 m3) (576,000,000 US gallons) of water in Yellowstone Lake, creating colossal waves that unsealed a capped geothermal system and led to the hydrothermal explosion that formed Mary Bay.[45][46]

Further research shows that very distant earthquakes reach and have effects upon the activities at Yellowstone, such as the 1992 7.3 magnitude Landers earthquake in California’s Mojave Desert that triggered a swarm of quakes from more than 800 miles (1,300 km) away, and the 2002 7.9 magnitude Denali fault earthquake 2,000 miles (3,200 km) away in Alaska that altered the activity of many geysers and hot springs for several months afterward.[47]

In 2016, the United States Geological Survey announced plans to map the subterranean systems responsible for feeding the area's hydrothermal activity. According to the researchers, these maps could help predict when another supereruption occurs.[48]

See also


  1. ^ USGS. "Yellowstone Volcano Observatory". United States Geological Survey.
  2. ^ "Yellowstone". Global Volcanism Program. Smithsonian Institution. Retrieved December 31, 2008.
  3. ^ a b c d Lowenstern, Jacob B.; Christiansen, Robert L.; Smith, Robert B.; Morgan, Lisa A.; Heasler, Henry (May 10, 2005). "Steam Explosions, Earthquakes, and Volcanic Eruptions—What's in Yellowstone's Future? – U.S. Geological Survey Fact Sheet 2005–3024". United States Geological Survey. Cite journal requires |journal= (help)
  4. ^ as determined by geological field work conducted by Bob Christiansen of the United States Geological Survey in the 1960s and 1970s.
  5. ^ Naomi E Matthews et al., 2015, "Age of the Lava Creek supereruption and magma chamber assembly at Yellowstone based on 40Ar/39Ar and U-Pb dating of sanidine and zircon crystals" DOI: 10.1002/2015GC005881
  6. ^ "Yellowstone Caldera, Wyoming—USGS". Cascade Volcano Observatory. United States Geological Survey. January 22, 2003. Retrieved December 30, 2008.
  7. ^ Johnston, Stephen T.; Wynne, P. Jane; Francis, Don; Hart, Craig J. R.; Enkin, Randolph J.; Engebretson, David C. (1996). "Yellowstone in Yukon: The Late Cretaceous Carmacks Group". Geology. 24 (11): 997, 998. Bibcode:1996Geo....24..997J. doi:10.1130/0091-7613(1996)024<0997:YIYTLC>2.3.CO;2.
  8. ^ "Yellowstone hotspot track". Lamont-Doherty Earth Observatory. Retrieved June 10, 2010.
  9. ^ Yellowstone Volcanic Hazards, USGS. (March 1, 2012). Retrieved on December 31, 2013.
  10. ^ West Thumb Lake is not to be confused with West Thumb Geyser Basin. The caldera created West Thumb Lake, and the underlying Yellowstone hotspot keeps West Thumb Geyser Basin active. See Fig. 22 Archived June 10, 2013, at the Wayback Machine. See also File:Yellowstone Caldera map2.JPG.
  11. ^ Newhall, Christopher G.; Dzurisin, Daniel (1988) Historical Unrest at Large Calderas of the World: U.S. Geological Survey Bulletin 1855
  12. ^ This qualitative statement is easily verified by reviewing the Yellowstone area in Google Earth
  13. ^ "Origin and evolution of silicic magmatism at Yellowstone" (PDF). University of Oregon.
  14. ^ "Secrets of supervolcanoes" (PDF). University of Oregon.
  15. ^ "Introduction to hydrothermal (steam) explosions in Yellowstone". Yellowstone National Park. Yellowstone Net. Retrieved December 31, 2008.
  16. ^ Witze, Alexandra (2013). "Large magma reservoir gets bigger". Nature. doi:10.1038/nature.2013.14036.
  17. ^ "USGS: Volcano Hazards Program – Yellowstone Volcano Observatory Featured Articles Archive". Retrieved April 4, 2014.
  18. ^ Foulger, Gillian (February 8, 2006). "Yellowstone". Retrieved February 10, 2008.
  19. ^ Christiansen, Robert L.; Foulger, G.R.; Evans, John R. (2002). "Upper-mantle origin of the Yellowstone hotspot". Geological Society of America Bulletin. 114 (10): 1245–1256. Bibcode:2002GSAB..114.1245C. doi:10.1130/0016-7606(2002)114<1245:UMOOTY>2.0.CO;2.
  20. ^ See list of off-line references in
  21. ^ Ivanov, Alexei V. (February 7, 2007). "The Columbia River Flood Basalts: Consequence of subduction-related processes". Retrieved December 31, 2008.
  22. ^ Zhou, Ying (2018), "Anomalous mantle transition zone beneath the Yellowstone hotspot track", Nature, 11: 449–453, doi:10.1038/s41561-018-0126-4, retrieved July 31, 2018
  23. ^ "Yellowstone National Park Earthquake listings". Retrieved April 20, 2013.
  24. ^ "Yellowstone Earthquake Swarms". Yellowstone Volcano Observatory. Retrieved January 1, 2009.
  25. ^ a b "January 2010 Yellowstone Seismicity Summary". Retrieved February 1, 2010.
  26. ^ "Archive of Yellowstone Updates for 2009".
  27. ^ "UUSS Webicorder (Seismogram) at Lake for December 31, 2008". Retrieved January 1, 2009.
  28. ^ Johnson, Kirk (January 31, 2010). "Hundreds of Quakes Are Rattling Yellowstone". The New York Times. Retrieved January 23, 2014.
  29. ^ Zuckerman, Laura. "Yellowstone National Park rattled by largest earthquake in 34 years". Reuters. Retrieved March 31, 2014.
    Gedeon, Jacqueline (March 31, 2014). "4.8 magnitude earthquake hits Yellowstone National Park". KECI. Montana. Retrieved April 4, 2018.
  30. ^ Zachos, Elaina (February 21, 2018). "Earthquake Swarms Are Shaking Yellowstone's Supervolcano. Here's What That Means". National Geographic. Retrieved April 4, 2018.
    Bartels, Meghan (February 20, 2018). "Yellowstone Supervolcano Earthquake Swarm Hits 200 Shakes In Less Than Two Weeks". Newsweek. Retrieved April 4, 2018.
  31. ^ "Undine Falls, Lava Creek, Yellowstone National Park". United States Geological Survey. Retrieved January 2, 2009.
  32. ^ John Timmer (November 8, 2007). "Yellowstone recharges". Retrieved November 8, 2007.
  33. ^ Smith, Robert B.; Chang, Wu-Lung; Siegel, Lee (November 8, 2007). "Yellowstone rising: Volcano inflating with molten rock at record rate". University of Utah Public Relations (Press release). EurekAlert! (American Association for the Advancement of Science).
  34. ^ Molten Rock Fills Yellowstone Volcano at Record Rate Newswise, Retrieved on September 2, 2008.
  35. ^ "Recent ups and downs of the Yellowstone Caldera". Yellowstone Volcano Observatory. United States Geological Survey. September 28, 2008. Retrieved December 31, 2008.
  36. ^ Smith, Robert B.; Jordan, Michael; Steinberger, Bernhard; Puskas, Christine M.; Farrell, Jamie; Waite, Gregory P.; Husen, Stephan; Chang, Wu-Lung; O'Connell, Richard (November 20, 2009). "Geodynamics of the Yellowstone hotspot and mantle plume: Seismic and GPS imaging, kinematics and mantle flow" (PDF). Journal of Volcanology and Geothermal Research. 188 (1–3): 26–56. Bibcode:2009JVGR..188...26S. doi:10.1016/j.jvolgeores.2009.08.020.
  37. ^ Alert Archive Search.
  38. ^ Current Alerts for U.S. Volcanoes.
  39. ^ GPS Station: WLWY – Data Products – Time Series Plots.
  40. ^ "Monitoring Upgrades Result in New Insight Into Yellowstone's Magma System" (Press release). Yellowstone Volcano Observatory (USGS). December 19, 2013. Retrieved January 2, 2014.
  41. ^ Burnett, Jim (January 1, 2014). "Reactions To Yellowstone Supervolcano Study Ranged From Hysteria To Ho-Hum". National Parks Traveller. Retrieved January 2, 2014.
  42. ^ a b Richard A. Lovett (September 20, 2012). "Yellowstone Supervolcano Discovery—Where Will It Erupt?". National Geographic.
  43. ^ Nasa's ambitious plan to save earth from a supervolcano
  44. ^ No, NASA Isn’t Going to Drill to Stop Yellowstone from Erupting
  45. ^ "Frequently asked questions about recent findings at Yellowstone Lake". Yellowstone Volcano Observatory. United States Geological Survey. September 11, 2008. Retrieved December 31, 2008.
  46. ^ "Tsunami linked to Yellowstone crater". USA Today. January 14, 2008. Retrieved December 31, 2008.
  47. ^ "Quake in Alaska Changed Yellowstone Geysers". University of Utah. May 27, 2004. Retrieved December 31, 2008.
  48. ^ "We're About to Find Out What's Rumbling Below The Yellowstone Supervolcano". Science Alert. Retrieved May 22, 2017.

Further reading

  • Breining, Greg (2007). Super Volcano: The Ticking Time Bomb beneath Yellowstone National Park. St. Paul, MN: Voyageur Press. ISBN 978-0-7603-2925-2. A popularized scientific look at the Yellowstone area's geological past and potential future
  • Vazquez, J.A.; Reid, M.R. (2002). "Time scales of magma storage and differentiation of voluminous rhyolites at Yellowstone caldera". Contributions to Mineralogy and Petrology. Wyoming. 144 (3): 274–285. Bibcode:2002CoMP..144..274V. doi:10.1007/s00410-002-0400-7.
  • Sutherland, Wayne; Sutherland, Judy (2003). Yellowstone Farewell. Spur Ridge. A novel looking at an eruption in the Yellowstone Caldera written by a practicing Wyoming geologist. Contains a wealth of technical details on the geology of western Wyoming

External links

1959 Hebgen Lake earthquake

The 1959 Hebgen Lake earthquake (also known as the 1959 Yellowstone earthquake) occurred on August 17 at 11:37 pm (MST) in southwestern Montana, United States. The earthquake measured 7.2 on the Moment magnitude scale, caused a huge landslide, resulted in over 28 fatalities and left US$11 million (equivalent to $94.54 million in 2018) in damage. The slide blocked the flow of the Madison River, resulting in the creation of Quake Lake. Significant effects of the earthquake were also felt in nearby Idaho and Wyoming, and lesser effects as far away as Puerto Rico and Hawaii.The 1959 quake was the strongest and deadliest earthquake to hit Montana, the second being the 1935–36 Helena earthquakes that left 4 people dead. It also caused the worst landslides in the Northwestern United States since 1927.

2012 (film)

2012 is a 2009 American disaster film co-written and directed by Roland Emmerich. The film was produced by Harald Kloser, Mark Gordon and Larry J. Franco. Kloser wrote the screenplay with Emmerich, and, the film was distributed by Columbia Pictures and produced by Emmerich's Centropolis Entertainment. The plot follows novelist Jackson Curtis as he attempts to bring his family to safety as the world is destroyed by a series of extreme natural disasters. The film refers to Mayanism and the 2012 phenomenon in its portrayal of cataclysmic events. Filming, originally planned for Los Angeles, began in Vancouver in August 2008.The film stars John Cusack, Chiwetel Ejiofor, Amanda Peet, Oliver Platt, Thandie Newton, Danny Glover and Woody Harrelson.

After a lengthy advertising campaign which included the creation of a website from its main character's point of view and a viral marketing website on which filmgoers could register for a lottery number to save them from the ensuing disaster, 2012 was released on November 13, 2009, to a commercial success with grossing over $769 million worldwide against production budget of $200 million, becoming the fifth highest-grossing film of 2009. However, the film received mixed reviews from critics, which criticized the runtime, screenwriting and plot, but was praised for its visual effects and production design.


A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber/reservoir in a volcanic eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is lost. The ground surface then collapses downward into the emptied or partially emptied magma chamber, leaving a massive depression at the surface (from one to dozens of kilometers in diameter). Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Only seven caldera-forming collapses are known to have occurred since 1900, most recently at Bárðarbunga volcano, Iceland in 2014.

Cascadia (bioregion)

The concept of Cascadian bioregionalism is closely identified with the environmental movement. In the early 1970s, the contemporary vision of bioregionalism began to be formed through collaboration between natural scientists, social and environmental activists, artists and writers, community leaders, and back-to-the-landers who worked directly with natural resources. A bioregion is defined in terms of the unique overall pattern of natural characteristics that are found in a specific place. The main features are generally obvious throughout a continuous geographic terrain and include a particular climate, local aspects of seasons, landforms, watersheds, soils, and native plants and animals. People are also counted as an integral aspect of a locale's life, as can be seen in the ecologically adaptive cultures of early inhabitants, and in the activities of present-day reinhabitants who attempt to harmonize in a sustainable way with the place where they live.The Cascadia bioregion contains 75 distinct ecoregions, and extends for more than 2500 miles from the Copper River in Southern Alaska, to Cape Mendocino in the South, and east as far as the Yellowstone Caldera and continental divide. Cascadian bioregionalism deals with the connected ecological, environmental, economic, and cultural ties that are prevalent throughout the U.S. Pacific Northwest and distance the area from their eastern counterparts. The argument is that those in Washington and Oregon in the United States have much more in common with those in British Columbia, Canada, than those in Washington D.C..The Cascadia Bioregion is also referred to as the Pacific Northwest Bioregion and encompasses all of the state of Washington, and portions of Oregon, Idaho, California, Nevada, Wyoming, Montana, Alaska, Yukon, and British Columbia. Bioregions are geographically based areas defined by land or soil composition, watershed, climate, flora, and fauna. The Cascadia Bioregion claims the entire watershed of the Columbia River (as far as the Continental Divide), as well as the Cascade Range from Northern California well into Canada. It's also considered to include the associated ocean and seas and their ecosystems out to the continental slope. The delineation of a bioregion has environmental stewardship as its primary goal, with the belief that political boundaries should match ecological and cultural boundaries.

The area from Vancouver, B.C. down to Portland, Oregon has been termed a megaregion by the U.S. and Canadian governments, especially along the 'Cascadian Corridor'. Megaregions are defined as areas where "boundaries begin to blur, creating a new scale of geography now known as the megaregion. These areas have interlocking economic systems, shared natural resources, and ecosystems, and common transportation systems link these population centers together. This area contains 17% of Cascadian land mass, but more than 80% of the Cascadian population. The Canada–US border is diminishing in the face of further economic, political and cultural integration with such programs as the enhanced drivers license program – which can be used to get across the Canada–US border between Washington and British Columbia.

Greater Yellowstone Ecosystem

The Greater Yellowstone Ecosystem (GYE) is one of the last remaining large, nearly intact ecosystems in the northern temperate zone of the Earth. It is located within the northern Rocky Mountains, in areas of northwestern Wyoming, southwestern Montana, and eastern Idaho, and is about 18 million acres. Yellowstone National Park and the Yellowstone Caldera 'hotspot' are within it.Conflict over ecological and resource management has been controversial, and the area is a flagship site among conservation groups that promote ecosystem management. The Greater Yellowstone Ecosystem (GYE) is one of the world's foremost natural laboratories in landscape ecology and Holocene geology, and is a world-renowned recreational destination. It is also home to the diverse native plants and animals of Yellowstone.

Henry's Fork Caldera

The Henry's Fork Caldera in eastern Idaho is a caldera located an area known as Island Park, west of Yellowstone National Park. The caldera was formed by an eruption 1.3 million years ago of the Yellowstone hotspot, that had a volume of 280 km3 (67 cu mi) and is the source of the Mesa Falls Tuff.

The Henry's Fork Caldera is nested inside of the Island Park Caldera, and the calderas share a rim on the western side. The earlier Island Park Caldera is much larger and more oval and extends well into Yellowstone Park. Although much smaller than the Island Park Caldera, the Henry's Fork Caldera is still sizeable at 18 miles (29 km) long and 23 miles (37 km) wide and its curved rim is plainly visible from many locations in the Island Park area. Of the many calderas formed by the Yellowstone hotspot, including the later Yellowstone Caldera, the Henry's Fork Caldera is the only one that is currently clearly visible. It is one of a succession of supervolcanoes and calderas that formed the Snake River Plain.

The Henrys Fork of the Snake River flows through the Henry's Fork Caldera and drops out at Upper and Lower Mesa Falls. The caldera is bounded by the Ashton Hill on the south, Big Bend Ridge and Bishop Mountain on the west, by Thurmon Ridge on the North and by Black Mountain and the Madison Plateau on the east.

The Henry's Fork caldera is in an area called Island Park, known for its beautiful forests, large springs, clear streams, waterfalls, lakes, ponds, marshes, wildlife, and fishing. Harriman State Park is situated within the caldera. The peaks of the Teton Range in adjacent Wyoming are visible to the southeast. Snowmobiling, fishing, and Nordic skiing, and wildlife viewing are popular activities in the area.

Huckleberry Ridge Tuff

The Huckleberry Ridge Tuff is a tuff formation created by the Huckleberry Ridge eruption that formed the Island Park Caldera that lies partially in Yellowstone National Park, Wyoming and stretches westward into Idaho into a region known as Island Park. This eruption of 2,200 km³ of material is thought to be the largest known eruption in the Yellowstone Hotspot's history. This eruption, 2.1 million years ago, is the third most recent large caldera forming eruption from the Yellowstone hotspot. It was followed by the Mesa Falls Tuff and the Lava Creek Tuff eruptions.

Island Park Caldera

The Island Park Caldera, in the U.S. states of Idaho and Wyoming, is one of the world's largest calderas, with approximate dimensions of 80 by 65 km. Its ashfall is the source of the Huckleberry Ridge Tuff that is found from southern California to the Mississippi River near St. Louis. This super-eruption of approximately 2,500 km3 (600 cu mi) occurred 2.1 Ma (million years ago) and produced 2,500 times as much ash as the 1980 eruption of Mount St. Helens. Island Park Caldera has the smaller and younger Henry's Fork Caldera nested inside it.The caldera clearly visible today is the later Henry's Fork Caldera, which is the source of the Mesa Falls Tuff. It was formed 1.3 Ma in an eruption of more than 280 km3 (67 cu mi). The two nested calderas share the same rim on their western sides, but the older Island Park Caldera is much larger and more oval and extends well into Yellowstone National Park. The Island Park Caldera is sometimes referred to as the First Phase Yellowstone Caldera or the Huckleberry Ridge Caldera.

To the southwest of the caldera lies the Snake River Plain, which was formed by a succession of older calderas marking the path of the Yellowstone hotspot. The plain is a depression, sinking under the weight of the volcanic rocks that formed it, through which the Snake River winds. Other observable volcanic features in the plain include: the Menan Buttes, the Big Southern Butte, Craters of the Moon, the Wapi Lava Field and Hell's Half Acre.

These calderas are in an area called Island Park that is known for beautiful forests, large springs, clear streams, waterfalls, lakes, ponds, marshes, wildlife, and fishing. Harriman State Park is located in the caldera. Snowmobiling, fishing, and Nordic skiing, and wildlife viewing are popular activities in the area. The peaks of the Teton Range to the southeast are visible from places in the caldera.

Lake Corcoran

Lake Corcoran (also known as Lake Clyde, after Clyde Wahrhaftig, an American geophysicist) is an ancient lake that covered the Central Valley of California.

The lake existed in the valleys of the Sacramento River and the San Joaquin River. An alternate view presumes that the lake covered only the southern parts of the Central Valley. The total surface covered by the lake amounts to about 30,000–50,000 square kilometers (12,000–19,000 sq mi). Buena Vista Lake, Kern Lake and Tulare Lake are remnants of Lake Corcoran.The lake is the source of the Corcoran Clay, a lacustrine unit of the Tulare and Turlock Lake formations. It also influenced sedimentation off the coast of California.The lake existed between about 758,000 and 665,000 years ago. Clay deposition rates indicate that the lake lasted for 50,000 to 100,000 years. The Lava Creek Tuff of Yellowstone Caldera and the Bishop Tuff of the Long Valley Caldera were deposited in the Corcoran Clay. Before Lake Corcoran formed, the Central Valley was a bay open to the south via a passage, until 2 million years ago when the bay was separated from the ocean, probably due to northwestward movement of the Coast Ranges along the San Andreas Fault. Subsequently, the valley was no longer a bay and alternately drained and filled with water. The factors contributing to the formation of Lake Corcoran are not fully understood.The lake originally drained into Monterey Bay via the Salinas River, or at times not at all. Evaporation from this lake was a source of water for the Sierra Nevada and in lesser measure for the Basin and Range Province behind it. This contributed to the formation of large pluvial lakes in Nevada.600,000 years ago a new outlet formed in the present day San Francisco Bay, where it remains today. Sediments found south of San Francisco indicate that by 400,000 years ago the drainage was fully established. The overflow may have occurred at a time where glaciers were melting and when shifts in the jet stream during the marine oxygen isotope stage 6 caused increased precipitation in and runoff to the Central Valley. The overflow rapidly carved an outlet through Carquinez Strait, probably catastrophically, and drained the lake. The Upper Turbidite Unit of the Monterey submarine fan may have formed soon after this outflow, when sediment from the former lake was carried out of its new outlet and down to Monterey Bay by longshore drift.

Lava Creek Tuff

The Lava Creek Tuff is a tuff formation in Wyoming, Montana and Idaho, United States, created during the Lava Creek eruption around 630,000 years ago, which formed the Yellowstone Caldera.The Lava Creek Tuff is distributed in a radial pattern around the caldera and is formed of 1,000 km3 (240 cu mi) of ignimbrites.The tuff has been exposed by erosion at Tuff Cliff along the Gibbon River.

Lava Creek Tuff ranges in color from light gray to pale red in some locales. Rock texture of the tuff ranges from fine-grained to aphanitic and is densely welded. The maximum thickness of the tuff layer is approximately 180–200 m (590–660 ft).

Orange Mound Spring

Orange Mound Spring is one of the several hot springs in Yellowstone National Park. The name comes from its dark orange appearance caused by orange cyanobacteria living on the travertine, the rock that it is made of. The Orange Mound Spring is part of the Mammoth Hot Springs area of the park. The Orange Mound Spring is arguably most notable for its prominence above the ground, compared to the rest of the Mammoth Hot Springs, which are mostly flat and leveled terraces.

Resurgent dome

In geology, a resurgent dome is a dome formed by swelling or rising of a caldera floor due to movement in the magma chamber beneath it. Unlike a lava dome, a resurgent dome is not formed by the extrusion of highly viscous lava onto the surface, but rather by the uplift and deformation of the surface itself by magma movement underground. Resurgent domes are typically found near the center of very large open calderas such as Yellowstone Caldera or Valles Caldera, and in turn such calderas are often referred to as "resurgent-type" calderas to distinguish them from the more common (but much smaller) calderas found on shield volcanoes and stratovolcanoes.

The structure that makes a resurgent dome possible is a fracture zone made up of ring faults surrounded by concentric normal faults around the outside of the rings. During initial formation of the caldera these ring faults provide vents for ash-flow eruptions and are the point at which subsidence of the cauldron block occurs. Subsequent magma flows then push the cauldron block back up creating the dome.In the monitoring of volcanic hazards, resurgent domes are often intensively monitored, as an ongoing increase in elevation accompanied by seismic activity is certain evidence for magma rising beneath the surface.

Sheepeater Cliff

The Sheepeater Cliffs are a series of exposed cliffs made up of columnar basalt in Yellowstone National Park in the United States. The lava was deposited about 500,000 years ago during one of the periodic basaltic floods in Yellowstone Caldera, and later exposed by the Gardner River. The cliffs are noted as a textbook example of a basaltic flow with well defined joints and hexagonal columns. They were named after a band of Eastern Shoshone known as Tukuaduka (sheep eaters). Many of the exposed cliffs are located along a steep inaccessible canyon cut by the Gardner near Bunsen Peak, but some of the cliffs located just off the Grand Loop Road can be reached by car.


A supervolcano is a large volcano that has had an eruption with a Volcanic Explosivity Index (VEI) of 8, the largest recorded value on the index. This means the volume of deposits for that eruption is greater than 1,000 cubic kilometers (240 cubic miles).

Supervolcanoes occur when magma in the mantle rises into the crust but is unable to break through it and pressure builds in a large and growing magma pool until the crust is unable to contain the pressure. This can occur at hotspots (for example, Yellowstone Caldera) or at subduction zones (for example, Toba). Large-volume supervolcanic eruptions are also often associated with large igneous provinces, which can cover huge areas with lava and volcanic ash. These can cause long-lasting climate change (such as the triggering of a small ice age) and threaten species with extinction. The Oruanui eruption of New Zealand's Taupo Volcano (about 26,500 years ago) was the world's most recent VEI-8 eruption.

Supervolcano (film)

Supervolcano is a 2005 British-Canadian disaster television film that originally aired on 13 March 2005 on BBC One, and released by the BBC on 10 April 2005 on the Discovery Channel. It is centered on the speculated and potential eruption of the volcanic caldera of Yellowstone National Park. Its tagline is "Scientists know it as the deadliest volcano on Earth. You know Yellowstone."

Yellowstone Lake

Yellowstone Lake is the largest body of water in Yellowstone National Park. The lake is 7,732 feet (2,357 m) above sea level and covers 136 square miles (350 km2) with 110 miles (180 km) of shoreline. While the average depth of the lake is 139 ft (42 m), its greatest depth is at least 394 ft (120 m). Yellowstone Lake is the largest freshwater lake above 7,000 ft (2,100 m) in North America.In winter, ice nearly 3 ft (0.91 m) thick covers much of the lake except where shallow water covers hot springs. The lake freezes over by early December and can remain frozen until late May or early June.

Yellowstone National Park

Yellowstone National Park is an American national park located in Wyoming, Montana, and Idaho. It was established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872. Yellowstone was the first national park in the U.S. and is also widely held to be the first national park in the world. The park is known for its wildlife and its many geothermal features, especially Old Faithful geyser, one of its most popular features. It has many types of ecosystems, but the subalpine forest is the most abundant. It is part of the South Central Rockies forests ecoregion.

Native Americans have lived in the Yellowstone region for at least 11,000 years. Aside from visits by mountain men during the early-to-mid-19th century, organized exploration did not begin until the late 1860s. Management and control of the park originally fell under the jurisdiction of the Secretary of the Interior, the first being Columbus Delano. However, the U.S. Army was subsequently commissioned to oversee management of Yellowstone for a 30-year period between 1886 and 1916. In 1917, administration of the park was transferred to the National Park Service, which had been created the previous year. Hundreds of structures have been built and are protected for their architectural and historical significance, and researchers have examined more than a thousand archaeological sites.

Yellowstone National Park spans an area of 3,468.4 square miles (8,983 km2), comprising lakes, canyons, rivers and mountain ranges. Yellowstone Lake is one of the largest high-elevation lakes in North America and is centered over the Yellowstone Caldera, the largest supervolcano on the continent. The caldera is considered an active volcano. It has erupted with tremendous force several times in the last two million years. Half of the world's geysers and hydrothermal features are in Yellowstone, fueled by this ongoing volcanism. Lava flows and rocks from volcanic eruptions cover most of the land area of Yellowstone. The park is the centerpiece of the Greater Yellowstone Ecosystem, the largest remaining nearly-intact ecosystem in the Earth's northern temperate zone. In 1978, Yellowstone was named a UNESCO World Heritage Site.

Hundreds of species of mammals, birds, fish, and reptiles have been documented, including several that are either endangered or threatened. The vast forests and grasslands also include unique species of plants. Yellowstone Park is the largest and most famous megafauna location in the contiguous United States. Grizzly bears, wolves, and free-ranging herds of bison and elk live in this park. The Yellowstone Park bison herd is the oldest and largest public bison herd in the United States. Forest fires occur in the park each year; in the large forest fires of 1988, nearly one third of the park was burnt. Yellowstone has numerous recreational opportunities, including hiking, camping, boating, fishing and sightseeing. Paved roads provide close access to the major geothermal areas as well as some of the lakes and waterfalls. During the winter, visitors often access the park by way of guided tours that use either snow coaches or snowmobiles.

Yellowstone Volcano Observatory

The Yellowstone Volcano Observatory (YVO) is a volcano observatory that primarily monitors the Yellowstone Caldera in Yellowstone National Park in the United States. The observatory's jurisdiction also includes volcanic centers in the states of Colorado, Utah, Arizona, and New Mexico. As with other U.S. volcano observatories, it is funded through the United States Geological Survey Volcano Hazards Program.The observatory consists of 8 member agencies:

The USGS, the University of Utah, the University of Wyoming, Yellowstone National Park, the Montana Bureau of Mines and Geology, the Wyoming State Geological Survey, the Idaho Geological Survey and UNAVCO, Inc.YVO was founded in 2001, originally as a three-way partnership with the USGS, the University of Utah and Yellowstone National Park. It was expanded in 2013 to include all eight current organizationsAccording to the YVO website, the purpose of the observatory is: to monitor the volcanic system, to increase our scientific understanding of the Yellowstone volcanic and hydrothermal system, and to disseminate data, interpretations and accumulated knowledge to the public.The observatory undertook a monitoring plan in 2006 that served as the basis for upgrades undertaken by the Plate Boundary Observatory, and by the USGS under the auspices of the American Recovery and Reinvestment Act of 2009.In 2008, it published its initial response plan that sets up a series of internal protocols for data gathering and deliberation during geological events at Yellowstone. Staff from the various observatory partner agencies form several monitoring and information teams that assess geological and geophysical data. The document also outlines how the observatory would interact with the incident command system.

YVO provides a monthly update through its website as well as information statements for events that fall in between their normal updates. All updates are listed on the VHP Alert Page. Individuals can receive automated updates through the Volcano Notification Service.

In 2005, a BBC/Discovery docudrama entitled Supervolcano was released on cable television. The drama imagines the reaction of the Yellowstone Volcano Observatory to a super eruption at the Yellowstone Caldera. Producer Ailsa Orr credits YVO scientists as inspiration for the film's three primary characters. The YVO Scientist-in-Charge reflected on the hype associated with volcanism at Yellowstone in a 2005 magazine article.

Yellowstone hotspot

The Yellowstone hotspot is a volcanic hotspot in the United States responsible for large scale volcanism in Idaho, Montana, Nevada, Oregon, and Wyoming as the North American tectonic plate moved over it. It formed the eastern Snake River Plain through a succession of caldera-forming eruptions. The resulting calderas include the Island Park Caldera, the Henry's Fork Caldera, and the Bruneau-Jarbidge caldera. The hotspot currently lies under the Yellowstone Caldera. The hotspot's most recent caldera-forming supereruption, known as the Lava Creek eruption, took place 640,000 years ago and created the Lava Creek Tuff, and the most recent Yellowstone Caldera. The Yellowstone hotspot is one of a few volcanic hotspots underlying the North American tectonic plate; others include the Anahim and Raton hotspots.


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