Caldera chronicles: Yellowstone Lake sediment reveals huge hydrothermal explosions

Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week’s contribution is from Lisa Morgan, emeritus research geologist with the U.S. Geological Survey.

Hydrothermal explosions, unrelated to magmatic eruptions but rather to water flashing to steam in a confined area, have emerged as one of the most important and least understood geologic hazards in Yellowstone National Park and similar volcanic and hydrothermal terrains worldwide. Hydrothermal explosions require a sudden drop in pressure, which causes rapid expansion of high-temperature fluids, fragmentation, ejection of debris, and crater formation. The northern Yellowstone Lake area is a locus of numerous past hydrothermal explosions and is an ideal natural laboratory for detailed research into the timing and triggering mechanisms of these poorly understood hazards.

A sediment-coring campaign was conducted in Yellowstone Lake to better understand the frequency, distribution, and causes of hydrothermal explosions over the last 14,000 years. These cores provide a basis for understanding hydrothermal explosion deposits in sedimentary sequences on the bottom of the lake and supplement recent and ongoing research on hydrothermal fluid systems venting on the lake floor, some of which are among the hottest hydrothermal vents in all of Yellowstone National Park.

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