The Yellowstone Plateau Volcanic Field began forming around 2 Ma (million years ago).[7] It has had over 110 different eruptions and has created mostly rhyolitic plains, with over 6000 km3 of rhyolitic material formed.[7] Scientists have discovered three major eruptions that formed calderas. They used methods of geological mapping, with both satellites and field work, and potassium-argon dating, to discover the eruptions.[5] The three major eruptions are:
The first large eruption was about 2.08 Ma and created the Huckleberry Ridge Caldera.[4] This eruption produced more than 2,500 km2 of magma[7] through at least three volcanic vents that produced large ash sheets across the area.[4] This caldera had three main pulses of activity during its formation.[8]
The second large eruption was about 1.3 Ma and created the Henrys Fork Caldera.[4] This eruption produced more than 280 km2 of magma [7] and was nested within a portion of a larger caldera, the Huckleberry Ridge Caldera.[4]
The third large eruption was about 0.6 Ma and created the Yellowstone Caldera.[4] This eruption produced 1,000 km2 of magma [7] through at least two volcanic vents.[4] The Yellowstone Caldera is above a continental hot spot, the Yellowstone mantle plume.[8] After the caldera was formed, there were rhyolitic lava flows between 160,000 and 70,000 years ago.[8]
The Yellowstone Caldera is a resurgent caldera and has experienced resurgent doming.[8] The Yellowstone Caldera has two resurgent domes formed by magma upwelling called Sour Creek and Mallard Lakes.[8] The magma chambers under the Yellowstone Caldera provides heat and energy for large hydrothermal systems.[8][9] The Yellowstone Caldera has the greatest concentration of hydrothermal features in the world, and is an active system.[9] The magma, geothermal activity, and hydrothermal system can lead to caldera motion, ash clouds, and earthquakes, so the Yellowstone Caldera is labeled as a geohazard.[8] A large amount of the Yellowstone Plateau volcanic field is in the Yellowstone National Park.[5][4][8][9]
