Yellowstone National Park has a bubbling hot spring that researchers recently discovered has very special properties. The hydrothermal pool, known as the Doublet Pool, emits a sharp thud every 20 to 30 minutes, kicking up near-boiling water and the earth around it.
This regular vibration acts like a “thermometer” that reflects how much energy the pool is heating at the bottom, according to a new study.
The Doublet Pool is located in the Upper Yellowstone Geyser Basin and is about half the size of a tennis court, filled with tap water about 2.4 meters deep. Its unusual pulsations are the result of bubbles in the plumbing system that feeds it with water heated by super-hot magma pulsing beneath Yellowstone.
In other hot springs, this process can create a geyser of hot water and steam erupting from the pool. However, the water is not able to pressurize the pool, so this eruption does not occur – instead, it just makes a dull sound.
The scientists found that the frequency of strokes varied from year to year, from day to day, and even from hour to hour. For example, the interval of silence between beats was about 30 minutes in November 2016, then only 13 minutes in September 2018, and then increased to 20 minutes in November 2021.
The intrigued team tried to figure out what was causing this change. In doing so, they hope to gain some knowledge of Yellowstone’s wider hydrothermal vents.
Scientists believe it all comes down to heat transfer. In November 2016, with a very short lull interval from basin impacts, Ear Spring on nearby Geyser Hill erupted for the first time since 1957. After this activity, the water in the Doubletree Basin increased.
This incident showed how the heat under the Geyser Hill increased the temperature under the Doublet Basin. In other words, hydrothermal heating at the base of the basin influenced the rate of impacts.
Lin explains that it would take more than 100 household stoves to burn off enough heat to create a thud from the pool.
Just as the base of a pool is important, heat transfer at the surface of the water can also play a role. By studying the weather patterns and pool activity, the researchers found that the wind speed over the pools correlated with the interval of silence. Although this process is not fully understood, they suggest that it is a bit like blowing on hot coffee to cool it down.