Photo: Steamboat Geyser in the Norris Geyser Basin. This geyser has unpredictable, infrequent major eruptions of more than 300 feet, and frequent minor eruptions 10-40 feet.
Norris Geyser Basin: A Land in Flux
Yellowstone National Park’s Norris Geyser Basin has been gurgling, boiling and blowing off steam for a long time. The oldest thermal area in the park, scientists estimate that it’s been around in its present state for more than 115,000 years. Although the “present state” term is used loosely as features there change daily thanks to frequent disturbances from seismic activity and water fluctuations.
Periodically, Norris undergoes a large-scale change. Features throughout the basin will have their water level, temperature, pH, color and eruptive patterns alter, often significantly.
Geologists and water chemists have studied these disturbances, and there are several theories about why they occur. Some say the disturbances are a massive fluctuation in the underground reservoirs that provide water to the basin. After all, Norris has several channels, often called “stacked water systems,” that supply water to various parts of the area.
Other experts theorize that because the disturbance usually occurs in the autumn there is less surface water mixing with water from deep underground. The water from deep underground holds more silica and clogs the cracks and crevices that supply water, thereby creating a “disturbance” as pressure builds.
Bottom line: Nobody knows for sure why or when a large-scale change will happen. What we do know is that they’re exciting. Need some proof? In 1985 a small geyser called Porkchop became a continuous jet of steam and water. During the fall of 1989, at the onset of another disturbance, Porkchop clogged with silica and blew up, flinging rocks as far as 200 feet.
Although these large-scale changes are infrequent, they tend to last for a few weeks before Norris returns to its “normal” state, giving visitors ample time to head over to the area for the show.
Photo: Porkchop Geyser in Norris Back Basin. In 1985 this geyser became a continuous jet of steam and water. During the fall of 1989, at the onset of another disturbance, Porkchop clogged with silica and blew up, flinging rocks as far as 200 feet.
Ledge Geyser Erupts for First Time in Ten Years
With a jet engine roar and a mighty burst of steam and water, a large geyser that hadn’t erupted since 1998 surprised two hikers near the edge of Norris Geyser Basin in early June, 2008.
Lee Whittlesey, park historian, and Betsy Watry, of the Yellowstone Association, witnessed Ledge Geyser blast into life, with a plume of steam arching 100 feet high into the air.
There was other unusual activity at Norris that weekend, said Henry Heasler, Yellowstone’s lead geologist, as other sporadic geysers erupted and surface waters turned murky.
Heasler called the events part of a “thermal disturbance,” which means sudden shifts in activity. For example, Vixen Geyser started spewing water and steam again, while Pearl Geyser’s water changed from clear to opalescent.
And yet, because Ledge Geyser is off the beaten path and does not have an electronic monitor, has it really been quiet since 1998?
“We don’t really know,” he said.
As often as thermal disturbances turn on some of Yellowstone’s geothermal features, they can also turn things off.
According to geyser observation records, Ledge Geyser was perking right along in the early 1970s, but after a thermal disturbance happened in 1974, eruptions became fewer and fewer, until they stopped entirely in 1979.
Just to show how amazingly constant Old Faithful is, Ledge Geyser spouted again in 1993, falling silent yet again in 1998.
“It is a very dynamic system,” said Heasler, one of continual changes and discovery.
He compared the current scientific understanding of Yellowstone’s geothermal features to that of reading the very first paragraph of the first book in the Harry Potter series. How, he asked, could you tell where the story was going on the basis of one paragraph?
Still, that first paragraph is a grabber, said Heasler, as is the growing body of geology and geophysics in and around Yellowstone.
Nevertheless, science marches on and is documenting what happens in, around and under Yellowstone with an ever-growing array of sensitive instruments, satellites and computers.
“We’re working to monitor entire systems, so we can tell if a basin is changing,” said Heasler. “We want to get enough information to create a baseline understanding of what is and isn’t normal.”
Yellowstone’s Geothermal Research Observatory
To strengthen the long-term monitoring of volcanic and earthquake unrest in the Yellowstone National Park region, the U.S. Geological Survey (USGS), Yellowstone National Park, and University of Utah established the Yellowstone Volcano Observatory (YVO).
According to Dr. Jacob B. Lowenstern, USGS scientist-in-charge of the new observatory, the observatory will improve the overall efforts to monitor Yellowstone’s extraordinarily large and long-lived volcanic system. “This agreement is a natural evolution of our collective work over the years to track and study Yellowstone’s unrest. There is no increased threat of eruptive activity at Yellowstone to cause concern at this time. We hope to use YVO to share even more of what we are learning with the public, Park visitors, and nearby residents, and to be in a better position to provide warning of any future hazardous activity.”
At a broader and more purely scientific level is the National Science Foundation-funded EarthScope Project. Dozens of federal and state agencies and more than 50 universities are intent on assembling monitoring instruments, super computers and hundreds of scientists for an unprecedented understanding of the movement and deformation of the North American continent. EarthScope could do for geoscience what the human genome sequencing effort did for biology.
Heasler and company are partnering with EarthScope on a plate boundaries study, installing new GPS instruments to better understand the deformation of the park’s volcanic caldera. Working with USGS, the park is monitoring gases from geothermal features for public safety, said Heasler.
While there are new sensing monitors with the latest bells and whistles, Heasler acknowledged it would be nice to have more and newer instruments. A lot of the seismic devices in the park are older and only show up and down motions. EarthScope would like to get upgrades for greater sensitivity and horizontal, as well as vertical, movements.
Summer Projects Researching Geysers
“We’re also working with three universities (Utah University, Montana University and Montana State) to determine the best methodology of detecting heat radiating from Yellowstone,” said Heasler – satellite or airborne imagery.
The Norris Basin area will see USGS and University of Utah researchers measuring the age of groundwater, said Heasler, to define the area that recharges the geothermal features. “This is critical to protecting those systems,” said Heasler.
Finally, park and USGS researchers are going to be measuring chloride gas emissions from the geothermal features. A new USGS device will give readings every 15 minutes, said Heasler, when before, readings were taken 28 times a year. Analysis of those measurements can give new insight into how the magmatic system below the park connects with surface geothermal features, he said.
“We want to know when the system is excited and when it is taking a nap,” said Heasler. “Currently, it is very difficult to judge what is normal or truly unusual.”
All this new research means more work for Heasler and his office. There’s more equipment to maintain, equipment to get permitted and the greater need to access it for maintenance. “All of which impacts the park,” said Heasler. Visitors don’t come to Yellowstone expecting to see scientific instrumentation, and park officials are pretty careful to put these equipment sets where visitors won’t stumble upon them by accident. Still, Heasler recognizes an educational opportunity when he sees one and is prepared to talk to visitors and encourage them to look at the online data at the Yellowstone Volcano Observatory website.
Taken all together, said Heasler, the ongoing research advances both science and public safety.
“The park is better protected from a safety viewpoint,” he said, “and this is a very exciting time to be in Yellowstone [as a scientist].”
There’s still a substantial residual effect from last year’s publicity about the Yellowstone Supervolcano, thanks to the Discovery Channel and numerous articles around the country, he said.
“People are interested, and they’re curious to learn more,” said Heasler. “It has made them aware of aspects they weren’t aware of before. This is a great opportunity to educate visitors and other scientists about what is (and isn’t) known.”
Yellowstone Progress Reports
One basic misunderstanding the public has about science is that the public expects final, solid answers.
“Science isn’t like that,” said Heasler. The process and practice of science is the periodic emergence of “progress reports,” he said.
Two research papers this year about Yellowstone are a good illustration of that point, he said.
“Charles Wicks has thrown down the gauntlet,” said Heasler, referring to Wicks’ research on the deformation of the Yellowstone caldera this year. The challenge is for scientists who believe that hydrothermal fluids are causing caldera deformation – much like a blister – to present data that supports that theory, he said.
One way to resolve some questions raised by Wicks is to study the gravity or mass of what lies under the caldera – is it magma or is it water and steam?
The scientific community will then debate which theory makes the most sense, given the data, Heasler said. Eventually, the scientific community works toward a consensus understanding.
Similarly, said Heasler, the research by Bob Smith is very interesting, raising yet more questions. The magmatic plume identified by Smith is 600 kilometers deep and tilts off toward Dillon, Montana – 90 degrees off from the direction the North American plate is traveling, Heasler noted. How does that work?
The answers keep coming, said Heasler.
And so do the questions.