Woke geyser doesn’t predict Yellowstone volcanic eruptions, study finds

When Yellowstone National Park’s Steamboat Geyser – which pulls water higher than any active geyser in the world – woke up in 2018 after three and a half years of dormancy, some speculated it was a harbinger of possible explosive volcanic eruptions in the surrounding geyser basin. These so-called hydrothermal explosions can throw mud, sand and rocks into the air and release hot steam, endangering lives; such an explosion on White Island in New Zealand in December 2019 left 22 people dead.

A new study by geoscientists who study geysers casts cold water on the idea, finding little evidence of underground magma movement that would be a prerequisite for an eruption. The geysers lie just outside the country’s largest and most dynamic volcanic caldera, but no major eruptions have occurred in the past 70,000 years.

“Hydrothermal vents – basically hot water that explodes because it comes in contact with hot rocks – is one of the biggest dangers in Yellowstone,” said Michael Manga, professor of earth and earth sciences. planets at the University of California at Berkeley and lead author of the study. . “The reason they are problematic is that they are very difficult to predict; it is not clear if there are any precursors that would allow you to give a warning.”

He and his team found that as the ground around the geyser rose and the seismicity increased somewhat before the geyser reactivated and the area currently radiates a little more heat into the atmosphere, no other geyser dormant in the basin did not restart and the temperature of the groundwater propelling the Steamboat eruptions did not increase. In addition, no sequence of Steamboat eruptions other than the one that began in 2018 has occurred after periods of high seismic activity.

“We can’t find any evidence of a big rash to come. I think that’s an important thing to remember,” he said.

The study will be published this week in Proceedings of the National Academy of Sciences.

Manga, who has studied geysers across the world and created them in his own lab, set out with his colleagues to answer three main questions about Steamboat Geyser: Why did he wake up? Why is its period so variable, ranging from 3 to 17 days? and why does it shoot up so high?

The team found answers to two of these questions. By comparing the column heights of 11 different geysers in the United States, Russia, Iceland and Chile with the estimated depth of the water reservoir from which their eruptions originated, they found that the deeper the reservoir, the more the jet of eruption is high. Steamboat Geyser, with a reservoir about 25 meters (82 feet) below the ground, has the highest column – up to 115 meters, or 377 feet – while two geysers measured by Manga in Chile were among the lowest – eruptions about one meter (3 feet) high from reservoirs 2 and 5 meters underground.

“What you’re really doing is you fill a container, it hits a critical point, you empty it, and you run out of liquid that can burst until it fills up again,” he says. “The deeper you go, the higher the pressure. The higher the pressure, the higher the boiling temperature. And the hotter the water, the more energy it has and the higher the geyser.”

To explore the reasons for the variability of Steamboat Geyser, the team gathered records relating to 109 eruptions dating back to its reactivation in 2018. The records included weather and flow data, seismometer and ground deformation readings, and observations by geyser enthusiasts. They also looked at the previous active and dormant periods of Steamboat and nine other geysers in Yellowstone, as well as data on thermal emissions at the ground surface of the Norris Geyser Basin.

They concluded that the variations in precipitation and snowmelt were probably responsible for part of the variable period, and possibly the variable period of other geysers as well. In spring and early summer, with melting snow and rain, groundwater pressure pushes more water into the underground reservoir, providing more hot water to burst more frequently. In winter, with less water, lower groundwater pressure fills the reservoir more slowly, resulting in longer periods between eruptions. Because the water pushed into the reservoir comes from places even deeper than the reservoir, the water has been decades or centuries before rising to the surface, he said.

In October, members of the Manga team demonstrated the extreme impact of water shortages and drought on the geysers. They showed that Yellowstone’s iconic Old Faithful Geyser had completely ceased to erupt for about 100 years in the 13th and 14th centuries, based on radiocarbon dating of mineralized lodgepole pines that grew around the geyser during its dormancy. Normally, the water is too alkaline and the temperature too high for trees to grow near active geysers. The period of dormancy coincided with a long period of heat and drought in the western United States, known as the medieval climate anomaly, which may have caused the demise of several Native American civilizations in the West.

“Climate change will affect geysers in the future,” Manga said.

Manga and his team were unable to determine why Steamboat Geyser restarted on March 15, 2018, after three years and 193 days of inactivity, although the geyser is known to be much more variable than Old Faithful, which typically fires around every hour. the 90 days. minutes. They could not find any definitive proof that the new magma rising under the geyser caused its reactivation.

The reactivation may have to do with changes in the internal plumbing, he said. Geysers seem to need three ingredients: heat, water, and silica rocks – silicon dioxide. Because the hot water in geysers is continuously dissolving and redepositing silica – every time Steamboat Geyser erupts, it brings in about 200 kilograms, or 440 pounds of dissolved silica. Some of this silica is deposited underground and can modify the plumbing system under the geyser. Such changes could temporarily stop or reactivate eruptions if the pipe is diverted, he said.

Manga experimented with geysers in his lab to understand why they erupt periodically, and at least in the lab, it appears to be caused by loops or side chambers in the pipe that trap slowly flowing bubbles of vapor, heating the column of water above. until all the water can boil from top to bottom, exploding explosively in a column of water and steam.

Studies of water eruptions from geysers could provide insight into hot rock eruptions from volcanoes, he said.

“What we have asked are very simple questions and it is a little embarrassing not to be able to answer them, because it means that there are fundamental processes on Earth that we do not fully understand,” he said. declared Manga. “One of the reasons we argue that we need to study geysers is that if we can’t understand and explain how a geyser erupts, our hope of doing the same for magma is much lower.”