The reawakened geyser does not predict Yellowstone volcanic eruptions, study shows

The reawakened geyser does not predict Yellowstone volcanic eruptions, study shows

A 2019 eruption in Steamboat Geyser in the Norris Geyser basin of Yellowstone National Park. The geyser’s first documented activity was in 1878, and it has been switched on sporadically ever since, once for 50 years without breaking out. In 2018, it was reactivated after an interruption of three and a half years, for reasons that are still unclear. Credit: Photo of UC Berkeley by Mara Reed

When the Steamboat Geyser from Yellowstone National Park – which shoots water higher than any active geyser in the world – woke up again in 2018 after three and a half years of rest, some speculated that 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 and endanger lives; such an explosion on White Island in New Zealand in December 2019 killed 22 people.

A new study by geoscientists studying geysers throws cold water on the idea, and finds few indications of subterranean magma motion that would be a prerequisite for an eruption. The geysers sit just outside the country’s largest and most dynamic volcanic caldera, but no major eruptions have taken place over the past 70,000 years.

“Hydrothermal vents – basically hot water that explodes because it comes in contact with hot rock – are one of the biggest dangers in Yellowstone,” said Michael Manga, professor of earth and planetary sciences at the University of California, Berkeley, and the senior author said of the study. . “The reason they are problematic is that they are difficult to predict; it is not clear if there are forerunners that enable you to give warning.”

He and his team found that while the ground around the geyser rose and the seismicity increased slightly before the geyser reactivated and the area currently radiates slightly more heat into the atmosphere, no other dormant geysers in the basin resumed. , and the temperature of the groundwater that drives steamboat eruptions did not increase. There was also no other series of eruptions of Steamboat than those that began in 2018, after periods of high seismic activity.

“We find no evidence that there is a major eruption. I think it is an important takeaway,” he said.

The study will be published this week in 2008 Proceedings of the National Academy of Sciences.

Manga, who has studied geysers around the world and created in his own lab, decided with his colleagues to answer three main questions about Steamboat Geyser: Why did it wake up again? Why does the period vary between 3 and 17 days? and why does it spray so high?

The team found answers to two of the questions. By comparing the column heights of 11 different geysers in the United States, Russia, Iceland and Chile with the estimated depth of the reservoir water from which their eruptions come, they found that the deeper the reservoir, the higher the eruption radius. 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 that measured Manga in Chile are one of the lowest – eruptions about a meter (3 feet)) high from reservoirs 2 and 5 feet below the ground.

“What you’re really doing is you fill a container, it reaches a critical point, you empty it and then you run out of liquid which can burst until it refills,” he said. “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 investigate the reasons for Steamboat Geyser’s volatility, the team set records related to 109 eruptions that were reactivated in 2018. The records included data on weather and current flow, seismometers and soil deformations, and observations by geyser enthusiasts. They also looked at previous active and dormant periods of Steamboat and nine other Yellowstone geysers, and data on the thermal emission of the surface of the Norris Geyser basin.

They concluded that variations in rainfall and snowmelt were likely responsible for part of the variable period, and possibly also for the variable period of other geysers. In spring and early summer, with melting snow and rain, the groundwater pressure pushes more water into the underground reservoir, providing more hot water to erupt more frequently. During the winter, with less water, the lower water pressure fills the reservoir more slowly, leading to longer periods between eruptions. Because the water that is pushed into the reservoir comes from places that are even deeper than the reservoir, the water is decades or centuries old before it erupts to the surface again, he said.

In October, Manga’s team members showed that the extreme impact of water shortages and drought could be on geysers. They showed that the iconic Old Faithful Geyser from Yellowstone did not erupt for about 100 years in the 13th and 14th centuries, based on radiocarbon dating of mineralized lodge pole pine trees that grew around the geyser during the rest period. Normally the water is too alkaline and the temperature is too high for trees to grow near active geysers. The dormant period coincided with a long, hot, dry period in the western United States, called the medieval climate deviation, which possibly caused the disappearance of several Indians in the West.

“Climate change is going to affect geysers in the future,” Manga said.

Manga and his team could not 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 is usually about every 90 minutes. They could find no definitive evidence that new magma rising under the geyser caused its reactivation.

The reactivation may have to do with changes in the internal plumbing work, he said. Geysers apparently need three ingredients: heat, water and rocks of silica – silicon dioxide. Because the hot water in geysers constantly dissolves and replaces silica – every time a steamboat geyser erupts, it yields about 200 kilograms, or 440 pounds of dissolved silica. Some of these silica are deposited underground and can alter 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 bubbles of steam that slowly drip out and heat the water column above. until all the water can boil from top to bottom and explode in a column of water and steam.

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

“What we have asked are very simple questions and it is a bit embarrassing that we cannot answer them because it means that there are fundamental processes on earth that we do not quite understand,” Manga said. “One of the reasons we claim to study geysers is that if we can not understand and explain how a geyser erupts, our hopes of doing the same thing for magma are much lower.”


Geysers have loops in their plumbing work: periodic eruptions linked to underground turns and side chambers


More information:
Mara H. Reed et al., “The 2018 Revival and Eruption of Dynamics of Steamboat Geyser, the World’s Highest Active Geyser,” PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.2020943118

Provided by the University of California – Berkeley

Quotation: Re-awakened geyser does not predict Yellowstone volcanic eruptions, study shows (2021, January 4) January 4, 2021 from https://phys.org/news/2021-01-reawakened-geyser-yellowstone-volcanic-eruptions.html

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