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

Porkchop Geyser erupting in August 1989.

Yellowstone is home to the world’s largest-known hydrothermal explosions , including Mary Bay , Turbid Lake, and Elliott’s Crater on the north side of Yellowstone Lake, and Pocket Basin and Twin Buttes in Lower Geyser Basin . Numerous studies have focused attention on these geologic hazards , and especially the processes that may trigger or control them.…