Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week's contribution is from Scott Johnson, Science Communications Associate for UNAVCO.

The morning of May 11 was notable for a magnitude 4.2 earthquake 23 miles northeast of Yellowstone’s East Entrance, which was the largest quake in the park since 2017. But it was also notable for another reason—members of the Yellowstone Volcano Observatory consortium happened to be gathering in the park at the Mammoth Hot Springs Hotel for a simulation to practice responding to a hypothetical geological event!

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It was the first in-person meeting for YVO since 2018, and fortunately there were no additional real-world events after the magnitude 4.2 to disrupt the agenda. It was a great opportunity for the group to share some of their science, talk with National Park Service staff, and brainstorm new research and outreach efforts.

The “tabletop” exercise at the heart of the meeting was led by Jessica Ball of the California Volcano Observatory and John Ewert of the Cascades Volcano Observatory and Volcano Disaster Assistance Program (that’s the USGS international volcano response team). Drawing on past experience with events like the 2018 eruptions at Kīlauea, they presented a hypothetical timeline of geological unrest in Yellowstone, asking the group to discuss what actions should be taken at various steps along the way.

The scenario began in springtime—before the park was widely open to visitors but also before the snow had melted to enable easier travel. There are many permanent monitoring instruments around Yellowstone, but heightened activity in a specific location could require the deployment of additional temporary instruments in that area. This would require coordination between groups with available instruments, scientists deciding which instruments to place in which locations, and park staff providing logistics and administering permits.

A host of technologies would be relied upon for this focused data collection, from seismometers to gas sampling to satellite imagery. Yellowstone can present a wide range of hazards, and comprehensive data are critical to understanding the potential outcomes of any episode of unrest. For example, increased hydrothermal activity at geysers can be studied by gas and water chemistry sampling, while signs of ground deformation might motivate the installation of additional GPS instruments.

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Maintaining data flow out of the park—which relies on radio or satellite links for continuous stations—would be another important consideration, particularly with the increased data from added instruments. And given that much of the park is difficult to access, keeping staff on the ground safe as they collect data would require extra care.

Significant hazard events, like severe earthquake activity or hydrothermal explosions, would be coordinated by an incident command team that would manage everything from access (including by scientists) to safety and communications for everyone in the area. Walking through how these teams are constructed and discussing how to share information across all the groups involved was a major part of the value of the exercise.

As the hypothetical scenario played out, alert levels were updated according to observed events and trends in the data. Given the intense interest in Yellowstone, keeping the public up-to-date would be even more important than usual to minimize misinformation and confusion. The scenario involved disruptions to park activities—like the normal post-winter opening of certain areas—but these actions were targeted at keeping everyone safe in the end, which is the ultimate goal of any hazard response.

The existing YVO event response plan will now be updated to reflect current organizational structures and lessons drawn from the tabletop exercise. The response plan, and readiness exercises like the recent tabletop, ensure that everyone understands their role so assignments can be carried out efficiently in the event that YVO needs to react to something out of the ordinary. Yellowstone is a dynamic place, so it’s important to be well prepared!