Chile Volcano Similar To Yellowstone -
Mitch Battros - Earth Changes Media
Calderas are among the most spectacular and active volcanic features on Earth. Earthquakes, ground cracks, uplift or subsidence of the ground, and thermal activity such as hot springs, geysers, and boiling mud pots are common at many calderas. Such activity is caused by complex interactions among magma stored beneath a caldera, ground water, and the regional buildup of stress in the large plates of the Earth's crust. Significant changes in the level of activity at some calderas are common; these new activity levels can be intermittent, lasting for months to years, or persistent over decades to centuries. Although most caldera unrest does not lead to an eruption, the possibility of violent explosive eruptions warrants detailed scientific study and monitoring of some active calderas.
Yellowstone Caldera is one of the largest and most active calderas in the world. The spectacular geysers, boiling hot springs, and mud pots that have made Yellowstone famous - and even the strikingly beautiful Grand Canyon of Yellowstone through which the Yellowstone River plunges - owe their existence to the tremendous volcanic forces that have affected the region during the past 2 million years. Cataclysmic eruptions 2.0, 1.3, and 0.6 million years ago ejected huge volumes of rhyolite magma; each eruption formed a caldera and extensive layers of thick pyroclastic-flow deposits. The youngest caldera is an elliptical depression, nearly 80 kilometers long and 50 kilometers wide, that occupies much of Yellowstone National Park. The caldera is buried by several extensive rhyolite lava flows erupted between 75,000 and 150,000 years ago.
Chaiten Caldera has lain dormant for more than 9,400 years, with the last known eruption in 7420 B.C. The volcano's caldera dates to the Pleistocene (about 1.8 million to 12,000 years ago), and contains a lava dome that formed much more recently, within the Holocene (about 12,000 years ago to the present). The dome is formed of rhyolite, a highly viscous magma that is often associated with energetic and explosive eruptions, according to the Chilean National Geological Survey. Previous deposits of lava and pyroclastic material suggest that thousands of years ago, the volcano had an explosive history.
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