Scientists map Yellowstone’s underground water

Every year millions of visitors gather to watch geysers like Old Faithful spew water into the air. Tourists aren’t the only ones who marvel at the eruptions and hot springs and wonder how it happens. Scientists also admire the natural phenomena and have a few questions of their own.

“We don’t know where that water comes from, or how it gets there,” said Steven Holbrook, a professor of geophysics at the University of Wyoming and co-director of the Wyoming Center for Environmental Hydrology and Geophysics.

He plans to change that.

Holbrook is one of several investigators working on a project between the University of Wyoming, the U.S. Geological Survey and Aarhus University in Denmark to map Yellowstone’s subsurface water.

During the park’s closure before the winter season begins, researchers are flying a helicopter equipped with a 1400-pound  hula-hoop-shaped electromagnetic apparatus  over large swaths of Yellowstone to try to map what is happening below the surface.

“That is going to give us an unprecedented, three-dimensional view of the hydrothermal subsurface over a very large region,” Holbrook said. The Park Service has released a video of the helicopter in flight with the detection device.

Scientists don’t know where fluid reservoirs lie beneath the surface or how deep they might be, Holbrook said. They don’t know which thermal features draw from the same reservoirs, or if there are several that are connected or where the pathways run that draw water up to the geysers and into the air.

Nor do they know where the water originates, Holbrook said. It could come from nearby mountain ranges outside the park.

That means development, like a recently proposed gold mine, outside the park boundaries, could impact the resources inside Yellowstone, said Carol Finn, a scientist with the U.S. Geological Survey who is also a lead investigator on the water-mapping project. While this type of project hasn’t been undertaken in Yellowstone, Finn has done similar projects on volcanoes in other places including the Cascade Mountains.

The data generated by the project will help park managers better understand what will impact the geysers both inside and outside the park boundaries, she said.

Finn also hopes the data could give insight into infrequent, hydrothermal explosions that can occur, such as the one that happened in Yellowstone Lake thousands of years ago. It also will give insight into smaller-scale thermal activity — like the seemingly erratic eruptions of some geysers, or the appearance of new thermal features.

As a scientist, Finn said she wouldn’t go as far as to say the data would allow prediction of these types of explosions, or appearances of new thermal features. Nonetheless, the information would still be valuable, especially for the park to plan development in a way that will allow visitors to see the geysers and mud pots that make Yellowstone special, while also protecting people and existing and new natural features.

The data will also help scientists studying microbial ecosystems and bacteria found in the park, Holbrook said. Understanding the water system and how it impacts thermal features will help researchers understand the bacteria that live in the park.

Researchers will finish collecting the data in about a week, before the park opens for the winter. They’ve been mapping the upper and lower geyser basins, as well as the Mammoth and Norris corridor, Holbrook said. The helicopter flies a pattern similar to one people use when mowing their lawn, up and down a grid. The instrument never touches the ground, nor does it ever fly over the same place twice, in an effort to mitigate impact on the park and its wildlife. The magnetic signals it emits are harmless, Holbrook said.

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While they haven’t started to analyze the data, the scientists have taken an initial look.

“It’s incredible,” Holbrook said. “We are seeing incredible detail under Old Faithful and we can see the pathway under the hydrothermal fluids right up to the vent. I think we are going to have some major discoveries; I just don’t know what they are yet.”