Steamboat Geyser in Yellowstone National Park remains an enigma, much as it has been for nearly 150 years, refusing to maintain a schedule of eruptions or clearly reveal the geologic machinations that drive its explosive outbursts.

Some 30 miles to the south in the park's Upper Geyser Basin, Old Faithful remains largely faithful to its schedule of erupting every 90 minutes or so, Castle Geyser goes off every 14 or 15 hours, and Daisy spouts every 2.5 hours, give or take 15 minutes. But Steamboat, though famous as the world's physically largest geyser, is a puzzler.

Its short history dates only to 1878, when its first eruptions were noticed by P.W. Norris, Yellowstone's second superintendent, and they were rather puny by recent history, spitting boiling water only between 30 and 100 feet. Thirty-six years later, in 1914, Steamboat still wasn't drawing much notice, and wasn't even mentioned in the Haynes Official Guide to Yellowstone National Park.

Well, actually it was, though not by that name.

While the Hayden expedition in 1878 dubbed the geyser Steamboat because "the eruptions remind one of the sound of an old style paddle wheel steamboat," it also went by a number of other names, including Fissure Geyser, Double Crater Geyser, Noble Geyser, and Tippecanoe Geyser. Somewhere along the line it also was called New Crater Geyser, which was how the Haynes Guide referred to it in the 1914 edition.

The geyser, Haynes noted, "came into prominence during the fall of 1891, when quite a commotion, not unlike an earthquake, was observed. When it burst forth a great volume of water was forced out, flooding the ravine leading to the valley below. Since then it has setled down to ordinary eruptions, about every three minutes. The rock-covered crater prevents the discharge attaining any great height."

Ordinary indeed. According to The Geysers of Yellowstone, fifth edition, by T. Scott Bryan, Steamboat/New Crater rather quickly gained a reputation for spectacular eruptions.

The destruction the eruptions brought to the surrounding forest was unmistakable: trees were killed, huge rocks thrown about, and plants covered with sand and mud by eruptions well over 100 feet high.

While the geyser put on some stupdendous shows in 1888, 1890, 1891, 1892, 1894 and 1902 with eruptions that soared at least 100 feet into the sky, and one truly impressive blast in 1911 that was estimated at more than 250 feet, Steamboat then went silent for nearly 50 years.

What Drives Steamboat's Eruptions?

While Steamboat came roaring back to life in 1961, and continued to erupt into 1969, it's the latest period of activity that started in 2018 that has garnered much attention from researchers. A paper published in January 2020 attributed an uplift in the Norris Geyser Basin to "a magma intrusion event during 1996–2001. The uplift probably results from fluids that have been expelled from the intruded magma."

"The expelled fluids have accumulated at a shallow depth (most likely 2–3 kilometers), and the record number of eruptions of Steamboat Geyser since March 2018 are probably related to the resulting uplift," the authors continued. "The shallow nature of the magma‐derived fluid accumulation may represent an increased risk of hydrothermal explosions at and around Norris Geyser Basin."

But a paper published last week played down the risk of hydrothermal explosions in the basin.

"Hydrothermal explosions -- basically hot water exploding because it comes into contact with hot rock -- are one of the biggest hazards in Yellowstone," said Michael Manga, professor of earth and planetary sciences at the University of California, Berkeley, and the study's senior author. "The reason that they are problematic is that they are very hard to predict; it is not clear if there are any precursors that would allow you to provide warning."

That said, Manga pointed out that while Steamboat has seen increased activity, "no other dormant geysers in the basin have restarted, and the temperature of the groundwater propelling Steamboat's eruptions has not increased."

"We don't find any evidence that there is a big eruption coming. I think that is an important takeaway," he said.

A 2019 eruption of Steamboat Geyser in the Norris Geyser Basin of Yellowstone National Park. The geyser's first documented activity was in 1878, and it has turned off and on sporadically since, once going for 50 years without erupting. In 2018 it reactivated after a three-and-a-half-year hiatus, for reasons that are still unclear/UC Berkeley, Mara Reed

While dispatching with that concern, Manga and his team tried to answer why Steamboat came back to life in 2018, why its eruptions are sporadic and unpredictable, and why the geyser spouts so high.

The geyser's impressive eruptions, which can climb nearly 400 feet into the sky, have to do with the fact that the reservoir that fuels Steamboat's waterworks is 82 feet below the surface of the Earth. Being deeper than many other geysers' reservoirs, Steamboat's is under greater pressure, and as a result has a higher boiling point.

"What you are really doing is you are filling a container, it reaches a critical point, you empty it and then you run out of fluid that can erupt until it refills again," Manga said in a release from the University of California-Berkeley. "The deeper you go, the higher the pressure. The higher the pressure, the higher the boiling temperature. And the hotter the water is, the more energy it has and the higher the geyser."

The variability in the geyser's eruptions likely has to do with available water. In spring and summer snowmelt and rainfall help to rather quickly refill the reservoir, compared to fall and winter when there's scant available precipitation, the researchers noted.

Because of the role rain and snow play in fueling Steamboat, Manga and his colleagues predict that climate change would have an impact on the geyser's eruptions in the years ahead. They were able to determine that Old Faithful actually stopped erupting for about 100 years during the 13th and 14th centuries, based on radiocarbon dating of mineralized lodgepole pine trees that grew around the geyser during its dormancy, the university released said.

"That dormancy coincided with a lengthy warm, dry spell across the Western U.S. called the Medieval Climate Anomaly, which may have caused the disappearance of several Native American civilizations in the West," the release added.

As drought returns to the Rockies, geysers will likely become more sporadic, the researchers concluded.

The answer to the final question Manga had hoped to answer, why Steamboat went silent between 2015 and 2018, remains a mystery. There was no evidence that magma rising towards the surface was responsible. It could have to do with changes in the geyser's underground plumbing, he said, explaining that when Steamboat erupts it spews more than 400 pounds of dissolved silica, and some of that is reabsorbed into the ground and might affect the plumbing by blocking some piping.

"What we asked are very simple questions and it is a little bit embarrassing that we can't answer them, because it means there are fundamental processes on Earth that we don't quite understand," Manga said. "One of the reasons we argue we need to study geysers is that if we can't understand and explain how a geyser erupts, our hope for doing the same thing for magma is much lower."

Yellowstone's 2020 Volcanic Activity

Looking back at 2020 in Yellowstone's thermal basins, the scientist-in-charge of the Yellowstone Volcano Observatory said it was a pretty ho-hum year.

"There were 1,718 earthquakes located in the region, which is on the low side of the average 1,500–2,500 events per year.  In fact, 2020 was the third year in a row with less than 2,000 located earthquakes," noted Michael Poland. "The largest earthquake of the year was a three-way tie, with M3.1 events occurring in March, May, and November, all in the area between Norris Geyser Basin in Yellowstone National Park and Hebgen Lake, Montana. There were also 23 swarms of earthquakes in Yellowstone during 2020, accounting for about 50 percent of the total number of located earthquakes—also typical for the region."

As for Steamboat, Poland said it erupted 48 times, tying the record for annual eruptions set in 2019. "And just like last (2019), the shortest and longest time periods between eruptions were ~3 and 17 days, respectively," he said.

Elsewhere in the park, Giantess Geyser, near Old Faithful, erupted in August and September for the first time since 2014, said Poland. "Prior to 2011, the geyser erupted a few times every year before going largely quiet (except for one eruption in 2014).  Perhaps Giantess is returning to a more active phase!"

Giantess Geyser in eruption at approximately 10 a.m. MDT on August 26, 2020. Old Faithful is erupting in the center background/NPS, Stan Mordensky

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