Just why is the world’s most famous geyser so Faithful?

With content from University of Wyoming

WYOMING –Have you ever wondered what it looks like beneath Old Faithful? Or where the geyser’s waters come from and whether any life exists in that water?

University of Wyoming geology Professor Ken Sims and his colleagues—UW research scientist Brad Carr, also a member of UW’s Department of Geology and Geophysics, and Eric Boyd, an associate professor at Montana State University—hope to answer these questions. They recently were permitted by Yellowstone National Park to study Old Faithful up close to seek the answers.

UW researchers recently received permission to execute numerous tests and collect extensive data from Old Faithful geyser in Yellowstone National Park. (NPS, UW)

Funded by UW’s Roy Shlemon Quaternary Center, the National Science Foundation and NASA, Sims and his colleagues, along with their teams of students, were allowed to execute numerous tests and collect extensive data from the iconic geyser. Sims specializes in geochemistry, Carr in geophysics and Boyd in microbiology; together, the group studies what Sims terms “geohydrobiology,” or the study of how earth, water and life connect.

The multifaceted research uses new and different techniques to look at each of those aspects of Yellowstone’s hydrothermal system, the largest on any continent. In essence, the work focuses on the pulse of Old Faithful’s dynamics, where and how old its source waters are and how this whole process supports “extremophiles”—the extreme life that first existed on Earth and gets energy from chemical reactions in rocks instead of from the sun.

“This is a complicated system, but we have the right mix of geophysical, geochemical and biological tools,” Sims says.

After two weeks in the park, the group has now collected enough solid data to allow the members to submit several research papers for review and publication. But, that doesn’t mean Sims and company are done with their research. They already are looking toward another trip back to the park in April to continue to gain a better understanding of Old Faithful’s hydrothermal system.

“We know its surface geometry, but we don’t know the timing and pathways for ascent of the fluids that make Old Faithful erupt. Essentially, we have a two-dimensional understanding of a four-dimensional problem. We can imagine what it looks like under Old Faithful, but we have no knowledge of what it really looks like under there,” Sims says. “However, with this effort, we are changing that and quickly developing an understanding of the Old Faithful system and what makes it all work.”

Watch the trio discuss their research in this video from Yellowstone National Park.

More about Old Faithful

Old Faithful erupts in this c1938 National Park Service silkscreen for Yellowstone National Park. (NPS)

Old Faithful blows its top 17 times a day on average. That means (doing the math in our head) we are closing in on a million eruptions since Yellowstone was established as America’s first national park in 1872—about 905,930 or so. US ranger/naturalist Harry Woodward was the first to calculate a mathematical relationship between the duration and intervals of the eruptions in 1938. According to his math, we may have already squeezed out 1,000,000 eruptions.

Intervals between eruptions can range from 60 to 110 minutes. However, the time between eruptions has been slowly increasing in the past few decades to an average of 90 minutes apart today.

Scientists believe this to be a result of area earthquakes affecting subterranean water levels—most notably the Hebgen Lake earthquake of 1959 and the 1983 Borah Peak earthquakes.

Eruptions spew between 3,700 to 8,400 gallons of boiling water (water temperature at the vent is 204°F, steam temperature is 350°F or more) to a height of 106 to 184 feet. They last anywhere from 1.5 minutes to 5 minutes. The average height of an eruption is about 130 feet.

The reliability of Old Faithful can be attributed to the fact that it is not connected to any other thermal features of the Upper Geyser Basin.

How do they know when the next eruption will be?

One of the first things visitors to Old Faithful Inn notice is a clock predicting the time of the next geyser eruption. Authorities figure this out using a not-so-complicated formula that has proven to be 90% accurate give or take 10 minutes.

The time between eruptions has a bimodal distribution, with the mean interval being either 60 or 90 minutes.

It is dependent on the length of the prior eruption. Within a margin of error of ±10 minutes, Old Faithful will erupt either 60 minutes after an eruption lasting less than 2 1/2 minutes, or 90 minutes after an eruption lasting more than 2 1/2 minutes.

In the past, Old Faithful displayed two eruptive modes: short duration eruptions followed by a short interval, and a long duration eruption followed by a long interval. After a local earthquake in 1998, however, Old Faithful’s eruptions are more often of the long duration, long interval type.

And, finally, for you ‘slow television’ fans: the answer to the question you probably all have. Is Old Faithful going off right now? Why don’t you see for yourself?

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