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CalVO researchers collaborate with Yellowstone Volcano Observatory to determine rhyolite lava eruption intervals in caldera

May 3, 2019

In addition to studying volcanic processes and their associated hazards in California and Nevada, scientists at the California Volcano Observatory also collaborate with other volcano observatories to work on volcanic processes throughout the United States.

One collaboration is looking at the timing and frequency of volcanism associated with Yellowstone Caldera, located within Yellowstone National Park.

Yellowstone Caldera is famous for a super-eruption ~631,000 years ago that ejected 240 mi3 of material, but these catastrophic events only represent a small fraction of the system's 2.1-million-year eruptive history. More commonly, Yellowstone produces smaller rhyolite lava flows with volumes ranging from 0.1 mi3to 17 mi3, although these eruptions are still quite large (for comparison, Mount St. Helens in 1980 erupted ~0.06 mi3 of material). In the last 631,000 years, at least 28 rhyolite eruptions have occurred within Yellowstone Caldera. However, it is unknown whether these eruptions occurred steadily over this timeframe or whether multiple eruptions clustered over short time intervals. This information is important for understanding volcanic hazards posed by Yellowstone's magmatic system, because if eruptions are clustered in time then the occurrence of one eruption may indicate that the next eruption may follow closely.

Currently, research is underway at Yellowstone to quantify the frequency of these smaller rhyolite eruptions. To do this, USGS scientists are measuring the age of volcanic rocks using a technique called 40Ar/39Ar dating, which is based on the timing of radioactive decay of potassium to argon. Preliminary results suggest that these smaller rhyolite eruptions were highly clustered in time, erupting in discrete episodes. During one of these eruptive episodes, up to 7 different eruptions occurred within the caldera over period of a thousand years or less. As research continues, scientists hope to refine the estimates of how long these eruptive episodes lasted, and incorporate those estimates into volcanic hazard assessments for Yellowstone.

A digital elevation map of Yellowstone Caldera
Rhyolite lavas in the Yellowstone Caldera younger than 631,000 years