If another large, caldera-forming eruption were to occur at Yellowstone, its effects would be worldwide. Such a giant eruption would have regional effects such as falling ash and short-term (years to decades) changes to global climate. Those parts of the surrounding states of Montana, Idaho, and Wyoming that are closest to Yellowstone would be affected by pyroclastic flows, while other places in the United States would be impacted by falling ash (the amount of ash would decrease with distance from the eruption site). Such eruptions usually form calderas, broad volcanic depressions created as the ground surface collapses as a result of withdrawal of partially molten rock (magma) below. Fortunately, the chances of this sort of eruption at Yellowstone are exceedingly small in the next few thousands of years.
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How big is the magma chamber under Yellowstone?
Yellowstone is underlain by two magma bodies. The shallower one is composed of rhyolite (a high-silica rock type) and stretches from 5 km to about 17 km (3 to 10 mi) beneath the surface and is about 90 km (55 mi) long and about 40 km (25 mi) wide. The chamber is mostly solid, with only about 5-15% melt. The deeper reservoir is composed of basalt (a low-silica rock type) and extends from 20 to 50...
What is the difference between "magma" and "lava"?
Scientists use the term magma for molten rock that is underground and lava for molten rock that breaks through the Earth's surface.
When was the last time Yellowstone erupted?
The most recent volcanic activity at Yellowstone consisted of rhyolitic lava flows that erupted approximately 70,000 years ago. The largest of these flows formed the Pitchstone Plateau in southwestern Yellowstone National Park. Learn more: Yellowstone Eruption History The evolution of the Yellowstone Plateau Volcani Field: Past, present, and future!
Why are there so many earthquakes at Yellowstone?
Almost all earthquakes at Yellowstone are brittle-failure events caused when rocks break due to crustal stresses. Though we've been looking at Yellowstone for years, no one has yet identified "long-period (LP) events" commonly attributed to magma movement. If LP events are observed, that will NOT mean Yellowstone is getting ready to erupt. LP earthquakes commonly occur at other volcanoes in the...
Can we drill into Yellowstone to stop it from erupting?
In some cases, limited scientific drilling for research can help us understand magmatic and hydrothermal (hot water) systems; however, drilling to mitigate a volcanic threat is a much different subject with unknown consequences, high costs, and severe environmental impacts. In addition to the enormous expense and technological difficulties in drilling through hot, mushy rock, drilling is unlikely...
What type of eruption will Yellowstone have if it erupts again?
The most likely explosive event to occur at Yellowstone is actually a hydrothermal explosion (a rock hurling geyser eruption) or a lava flow. Hydrothermal explosions are very small; they occur in Yellowstone National Park every few years and form a crater a few meters across. Every few thousand years, a hydrothermal explosion will form a crater as much as a few hundred meters across. Though the...
How far would ash travel if Yellowstone had a large explosive eruption?
Knowledge about past eruptions of Yellowstone combined with mathematical models of volcanic ash dispersion help scientists determine where and how much ashfall will occur in possible future eruptions. During the three caldera-forming eruptions that occurred between 2.1 million and 640,000 years ago, tiny particles of volcanic ash covered much of the western half of North America. That ash was...
What is a supervolcano? What is a supereruption?
The term "supervolcano" implies a volcanic center that has had an eruption of magnitude 8 on the Volcano Explosivity Index (VEI), meaning that at one point in time it erupted more than 1,000 cubic kilometers (240 cubic miles) of material. In the early 2000s, the term “supereruption” began being used as a catchy way to describe VEI 8 eruptions. Explosive events of this size erupt so much magma that...
What are some examples of supervolcanoes?
Volcanoes that have produced exceedingly voluminous pyroclastic eruptions and formed large calderas in the past 2 million years include Yellowstone in northwest Wyoming, Long Valley in eastern California, Toba in Indonesia, and Taupo in New Zealand. Other 'supervolcanoes' would likely include the large caldera volcanoes of Japan, Indonesia, Alaska (e.g. Aniakchak, Emmons, Fisher), and other areas...
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- FAQ
How big is the magma chamber under Yellowstone?
Yellowstone is underlain by two magma bodies. The shallower one is composed of rhyolite (a high-silica rock type) and stretches from 5 km to about 17 km (3 to 10 mi) beneath the surface and is about 90 km (55 mi) long and about 40 km (25 mi) wide. The chamber is mostly solid, with only about 5-15% melt. The deeper reservoir is composed of basalt (a low-silica rock type) and extends from 20 to 50...
What is the difference between "magma" and "lava"?
Scientists use the term magma for molten rock that is underground and lava for molten rock that breaks through the Earth's surface.
When was the last time Yellowstone erupted?
The most recent volcanic activity at Yellowstone consisted of rhyolitic lava flows that erupted approximately 70,000 years ago. The largest of these flows formed the Pitchstone Plateau in southwestern Yellowstone National Park. Learn more: Yellowstone Eruption History The evolution of the Yellowstone Plateau Volcani Field: Past, present, and future!
Why are there so many earthquakes at Yellowstone?
Almost all earthquakes at Yellowstone are brittle-failure events caused when rocks break due to crustal stresses. Though we've been looking at Yellowstone for years, no one has yet identified "long-period (LP) events" commonly attributed to magma movement. If LP events are observed, that will NOT mean Yellowstone is getting ready to erupt. LP earthquakes commonly occur at other volcanoes in the...
Can we drill into Yellowstone to stop it from erupting?
In some cases, limited scientific drilling for research can help us understand magmatic and hydrothermal (hot water) systems; however, drilling to mitigate a volcanic threat is a much different subject with unknown consequences, high costs, and severe environmental impacts. In addition to the enormous expense and technological difficulties in drilling through hot, mushy rock, drilling is unlikely...
What type of eruption will Yellowstone have if it erupts again?
The most likely explosive event to occur at Yellowstone is actually a hydrothermal explosion (a rock hurling geyser eruption) or a lava flow. Hydrothermal explosions are very small; they occur in Yellowstone National Park every few years and form a crater a few meters across. Every few thousand years, a hydrothermal explosion will form a crater as much as a few hundred meters across. Though the...
How far would ash travel if Yellowstone had a large explosive eruption?
Knowledge about past eruptions of Yellowstone combined with mathematical models of volcanic ash dispersion help scientists determine where and how much ashfall will occur in possible future eruptions. During the three caldera-forming eruptions that occurred between 2.1 million and 640,000 years ago, tiny particles of volcanic ash covered much of the western half of North America. That ash was...
What is a supervolcano? What is a supereruption?
The term "supervolcano" implies a volcanic center that has had an eruption of magnitude 8 on the Volcano Explosivity Index (VEI), meaning that at one point in time it erupted more than 1,000 cubic kilometers (240 cubic miles) of material. In the early 2000s, the term “supereruption” began being used as a catchy way to describe VEI 8 eruptions. Explosive events of this size erupt so much magma that...
What are some examples of supervolcanoes?
Volcanoes that have produced exceedingly voluminous pyroclastic eruptions and formed large calderas in the past 2 million years include Yellowstone in northwest Wyoming, Long Valley in eastern California, Toba in Indonesia, and Taupo in New Zealand. Other 'supervolcanoes' would likely include the large caldera volcanoes of Japan, Indonesia, Alaska (e.g. Aniakchak, Emmons, Fisher), and other areas...
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