The world’s tallest active geyser is also one of its most mysterious, going dormant for years between periods of unpredictable, frequent eruptions.
Yellowstone National Park’s Steamboat Geyser sprang back to life in a big way three years ago, spewing boiling water up to 360 feet into the air with greater frequency than ever with no signs abating.
University of Utah geologists have been using this resurgent activity to gain a better understanding of Yellowstone’s hydrothermal features, particularly the enigmatic Steamboat, along with the nearby Cistern Spring, which cools and recedes every time Steamboat blows. Seismologist Jamie Farrell was retrieving portable instruments his team had placed around the geyser in June 2018, when it gurgled into action then exploded.
“I’ve seen Old Faithful go off hundreds and hundreds of times. Steamboat was on another level. I knew it was the tallest active geyser in the world, but it was just insane how powerful and energetic and high that thing was. It literally sounds like you’re sitting in front of a jet engine and you can feel it,” said Farrell, a research assistant professor with the U.’s Seismograph Stations. “You can see these good-sized chunks of rock being thrown in the air. It’s hard really to describe without actually seeing it.”
Steamboat Geyser is much different than the park’s most famous geyser, Old Faithful, whose eruptions have occurred with predictable regularity about 17 times a day to the delight of millions of park visitors over the decades. By contrast, Steamboat is anything but regular, and Farrell wants to find out why.
Closely studying the geyser now and after it goes back to sleep “would potentially provide us another indication why some geysers are predictable and some are just completely irregular. Old Faithful is very predictable,” Farrell said. “One hypothesis is that because it’s all by itself, it’s kind of isolated, so it doesn’t have to compete for water and heat and energy with another system.”
Steamboat, on the other hand, shares water and heat sources with other hydrothermal features, somehow connected via a hidden network of passages.
Farrell has been leading an ongoing study with U. colleagues and installed an array of seismographs around Steamboat and Cistern Spring that records a month’s worth of data. The plan is to characterize the geyser’s underground plumbing in hopes of determining how it’s connected to other park features and learn why it spouts water so high and for so long — and why it has resumed frequent eruptions.
Understanding the geyser’s underbelly
Yellowstone is home to more than 10,000 hydrothermal features, including fumaroles, mud pots and hot springs, in addition to several noisy geysers that hog most of the attention.
The U. team’s freshly published paper sheds light on Steamboat’s inner workings by using seismographic data to create three-dimensional images of Cistern and Steamboat’s plumbing, which drops at least 450 feet into the earth.
“We now have a baseline of what eruptive activity looks like for Steamboat,” said co-author Fan-Chi Lin, a U. geology professor. “When it becomes less active in the future, we can redeploy our seismic sensors and get a baseline of what nonactive periods look like. We then can continuously monitor data coming from real-time seismic stations by Steamboat and assess whether it looks like one or the other, and get a more real-time analysis of when it looks like it is switching to a more-active phase.”
Geysers are water-filled tubes in the earth rising to the surface above a magma chamber, which heats the water. As it boils, the water convulses upward and jets from a hole at the surface. Once the eruption is spent, the water settles back into the tube and the process repeats. What makes Steamboat so intriguing are the long periods of relative dormancy in which years go by with just a handful of eruptions.
Since its reawakening March 15, 2018, Steamboat has seen 133 major eruptions with the last one occurring two weeks ago. Before that, it hadn’t erupted since Sept. 3, 2014. The only other known eruption swarms were in 1982-83 (35 eruptions) and the mid-1960s, according to a list compiled by the park.
What happens when it erupts
Before Steamboat’s major eruptions, hot water rises 10 or more feet above Steamboat’s pool before it unleashes a skyward jet that often lasts a half-hour or more, followed by a steam phase that can persist for days. As Steamboat erupts, Cistern Spring disappears into the ground, then slowly refills, indicating a connection between the two.
“We wanted to see if we could learn more about Steamboat and to see if we can learn more about this connection, to see if we could actually image this connection between the two,” Farrell said. “That would potentially provide us another indication why some geysers are predictable and some are just completely irregular.”
The team’s latest round of data from is from 2019, when it recorded seven eruptions over a one-month period. The data showed Steamboat’s plumbing is vertical, dropping straight down for at least 450 feet.
“The Cistern plumbing system is really interesting in that it’s vertical for like the first 20 or 30 meters, then it switches to this diagonal dipping structure that goes down to the southeast. The bottom of that is 145 meters and it’s directly south of Steamboat,” Farrell said. “We can watch the activity migrate from that deep pool up to underneath Steamboat, and we can see this recharge as the systems get ready for the next eruption.”
The data failed to detect the connection between the two features. Why?
“One possibility is that connection is just deeper than what we could see with the array we put out,” Farrell said. “Or that connection is what we call aseismic. It is connected, but there’s no seismic signals from that conduit, so we can’t see it.”
Farrell’s team will return to Norris Geyser Basin in the coming months, after the snow melts. The plan is to install a larger array of instruments to see even farther beneath the ground under Steamboat to further plumb the secrets of one of the world’s most interesting geysers.