This Yellowstone hot spring’s rhythmic thump makes it a geo-thermometer

Yellowstone National Park is most famous for Old Faithful, a geyser with fairly predictable periodic eruptions that delight visiting tourists. But it's also home to many other geothermal features like Doublet Pool, a pair of hot springs connected by a small neck with the geothermic equivalent of a pulse. The pool "thumps" every 20-30 minutes, causing the water to vibrate and the ground to shake. Researchers at the University of Utah have measured those thumping cycles with seismometers to learn more about how they change over time. Among other findings, they discovered that the intervals of silence between thumps correlate with how much heat is flowing into the pool, according to a new paper published in the journal Geophysical Research Letters.

“We knew Doublet Pool thumps every 20-30 minutes,” said co-author Fan-Chi Lin, a geophysicist at the University of Utah. “But there was not much previous knowledge on what controls the variation. In fact, I don’t think many people actually realize the thumping interval varies. People pay more attention to geysers.”

Yellowstone's elaborate hydrothermal system is the result of shallow groundwater interacting with heat from a hot magma chamber. The system boasts some 10,000 geothermal features, including steam vents (fumaroles), mud pots, and travertine terraces (chalky white rock), as well as geysers and hot springs.