Geysers do not forecast explosive volcanic activity in Yellowstone

Geysers do not forecast explosive volcanic activity in Yellowstone. The reawakening of the world’s tallest active geyser is not a forewarning of explosive volcanic activity in Yellowstone National Park, according to a study from UC Berkeley. In 2018, the Steamboat Geyser entered into a prolonged period of frequent activity after three and a half years of dormancy.

Yellowstone National Park has over 10,000 hot springs and geysers. Some of the geysers erupt as frequently as 300 times a year, while others remain dormant for decades at a time. 

“Hydrothermal explosions – basically hot water exploding because it comes into contact with hot rock – are one of the biggest hazards in Yellowstone,” said study senior author Professor Michael Manga. “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.”

The researchers established that the ground around the Steamboat Geyser has risen, and that seismic activity increased somewhat before the geyser reawakened. In addition, the area is currently radiating more heat into the atmosphere. However, 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,” said Professor Manga, who has studied geysers around the world and created some in his own laboratory.

The experts set out to answer three questions about Steamboat Geyser, including why it reawakened and why its activity is so variable. The team also wanted to know how the geyser has the potential for such powerful explosions. While minor eruptions of 10 to 15 feet are much more frequent, major eruptions have thrown water more than 375 feet into the air. 

The researchers managed to answer two out of three questions. First, by comparing geysers in the United States, Russia, Iceland, and Chile, the team determined that the deeper the reservoir, the higher the eruption jet. Steamboat Geyser, with a reservoir about 82 feet below ground, has the highest column of up to 377 feet. Meanwhile, two of the other geysers that were measured in Chile had eruptions of only about three feet high from up to 16-foot-deep reservoirs.

“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,” said Professor Manga. “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 researchers also analyzed historical records that included weather data and seismometer and readings to predict which factors cause the variability of Steamboat’s eruptions, which ranges from three to 17 days. 

The study authors concluded that variations in rainfall and snowmelt were likely responsible for most of this variability. For example, melting snow and rainfall in the warmer months will fill the reservoir up faster, providing geysers with enough water to erupt more frequently.

Professor Manga and his team were unable to determine why Steamboat Geyser reawakened on March 15, 2018, after three years and 193 days of inactivity. They found no definitive evidence that it was triggered by new magma rising below the geyser.

According to Professor Manga, studies of water eruptions from geysers could give insight into the eruptions of hot rock from volcanoes.

“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.”

“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.”

The study is published in the Proceedings of the National Academy of Sciences.

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By Chrissy Sexton, Earth.com Staff Writer