Geyser Activity Does Not Foretell Yellowstone Volcanic Eruptions

Geyser Activity Does Not Foretell Yellowstone Volcanic Eruptions

Forbes·2021-01-06 06:01

Steamboat geyser in Norris Basin in Yellowstone National Park with hot steam, vapor, blue hot ... [+] springs and mountainsgettySteamboat Geyser in the Norris Geyser Basin of Yellowstone National Park is the world's tallest active geyser, shooting water between 90 and 120 meters (300-400 feet) high. Unlike other geysers, Steamboat does not erupt on a predictable schedule, with recorded intervals between major eruptions ranging from three days to fifty years. The geyser's first documented activity was in 1878. The geyser was dormant from 1911 to 1961. In 2018 it reactivated after three and a half years of dormancy, prompting speculations about an imminent reawakening of the Yellowstone supervolcano. The major geyser fields sit just outside the volcanic caldera, but no major eruptions have occurred here in the past 70,000 years.A new study by geoscientists published in the journal Proceedings of the National Academy of Sciencesshows that geyser activity is not directly linked to underground magma movement that would be a prerequisite to an eruption.Michael Manga, professor of earth and planetary sciences at the University of California, Berkeley, and the study's senior author, and his team found that, while the ground around the geyser rose and seismicity increased somewhat before the geyser reactivated and the area currently is radiating slightly more heat into the atmosphere, no other dormant geysers in the basin have restarted, and the temperature of the groundwater propelling Steamboat's eruptions has not increased. Also, no sequence of Steamboat eruptions other than the one that started in 2018 occurred after periods of high seismic activity.The activity of Steamboat Geyser is more likely linked to the morphology of its underground plumbing system and precipitation patterns in Yellowstone.By comparing the eruption heights of 11 different geysers in the United States, Russia, Iceland and Chile with the estimated depth of the reservoir of water from which their eruptions come, the researchers found that the deeper the reservoir, the higher the eruption jet. Steamboat Geyser, with a reservoir about 25 meters (82 feet) below ground, has the highest column - up to 122 meters, or 400 feet - while two geysers studied in Chile were among the lowest, with eruptions about a meter (3 feet) high from reservoirs 2 and 5 meters below ground.The deeper the geyser's plumbing system goes, the higher the water's weight and pressure on the bottom. The higher the pressure, the higher the boiling temperature. And the hotter the water is, the more energy it has and the higher the resulting steam eruption.The researchers also compared the timing of 109 eruptions going back to the geyser's reactivation in 2018 with variables like seismic activity, ground deformation rates, weather and streamflow data. They also looked at previous active and dormant periods of Steamboat and nine other Yellowstone geysers and ground surface thermal emission data from the Norris Geyser Basin. The intensity of tremors, ground deformation rates, and thermal emissions are used to monitor partially molten rock movements in the underground of Yellowstone.Finding no correlation between seismic activity and eruption intervals, the study concludes that variations in rainfall and snowmelt were probably responsible for part of the variable eruption activity, and possibly for the variable period of other geysers as well. In the spring and early summer, with melting snow and rain, the underground water pressure pushes more water into the underground reservoir, providing more hot water to erupt more frequently. During winter, with less water, lower groundwater pressure refills the reservoir more slowly, leading to longer periods between eruptions.Long-term activity is likely controlled by the rising or falling groundwater table, drought periods reflecting a decrease in geyser activity, as happened before 1961 and 2018 at Steamboat Geyser.

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