This 3-D view of the magmatic system beneath the Snake River Plain and Yellowstone National Park is inferred from magnetotelluric data. At each point on this surface, the magnetic field has a constant or lower value. The actual locations at which data were collected are shown by the dots on top. Yellowstone is indicated with an open circle. Note the conductive pathway to the Yellowstone caldera from beneath the eastern Snake River Plain. (Figure courtesy of Anna Kelbert. Source: Kelbert A., Egbert G.D., deGroot-Hedlin C. 2012. “Crust and upper mantle electrical conductivity beneath the Yellowstone Hotspot Track” Geology, v. 40, p. 447-450, doi:10.1130/G32655.1)

A geological mystery lies beneath the majestic beauty of Yellowstone National Park. Once thought solved, the enigma continues to unfold through the lens of a young science known as magnetotellurics.

As accepted theory goes, over the past 16 million years a rising plume of magma in the Earth’s mantle produced massive amounts of lava and ash in a path stretching from the Snake River Plain to its current caldera — a volcanic crater in Wyoming, the Yellowstone “supervolcano.” It is widely believed that the Yellowstone caldera currently sits on top of that hotspot, a vertical “blowtorch” in the mantle beneath the Earth’s crust. The North American tectonic plate slowly creeps over the plume of magma, no faster than the rate at which fingernails grow. The plume sometimes oozes and other times violently erupts lava across an area the size of Rhode Island. Adam Schultz, a geophysics professor in Oregon State University’s College of Earth, Ocean, and Atmospheric Sciences, describes this mantle hotspot idea as “almost a cartoon view that Earth scientists have of why you get features like Yellowstone.”

Magnetotellurics (MT), the study of the Earth’s electric and magnetic fields, may turn this cartoon view on its head. The use of magnetotelluric surveys has exploded in the last decade thanks to progress in computing technology and geophysical instrumentation. Schultz’s colleagues at Oregon State — Anna Kelbert and Gary Egbert  — have used magnetotellurics to reveal that large volumes of partially molten rock and potentially superheated water (hydrothermal systems) snake west underneath the crust and into the uppermost mantle west of Yellowstone. This molten trail continues westward along much of the Snake River Plain in Idaho and into Oregon. These findings complicate the expectation that a nearly vertical magma plume lies directly under the present day Yellowstone supervolcano, which was what is anticipated from a hotspot. Magnetotellurics has opened doors to stunning breakthroughs and fascinating discoveries, providing new perspectives that were once invisible to science.

Research assistant Tristan Peery, left, and Adam Schultz are analyzing changes in subsurface rock as part of a geothermal energy study by AltaRock, Inc. (Photo: Dennis Wolverton, courtesy of the Oregon Stater magazine)

From Magnetics to Melted Rock

With magnetotellurics, scientists measure variations in the direction and intensity of the planet’s natural magnetic and electric fields over time. They use these measurements to understand the properties of the rock, one of the most important being electrical conductivity. Generally, greater electrical conductivity can suggest the presence of extensively interconnected bodies of fluid within the rock. West of Yellowstone, magnetotellurics reveal a relatively shallow, hot, highly conductive region under the Snake River Plain.

Schultz compares magnetotelluric surveys to MRIs commonly used in medical diagnostics. In fact the underlying principles are similar. “If you go to a radiology department and they do a CT scan of your head, for example, they see some weird thing, and they’re not quite sure what it is. You have an MRI and go, ‘ah! that’s a brain tumor,’” says Schultz.

In the same way, MT can be thought of as a very large MRI. And just as doctors put together multiple types of scans to see inside our bodies, geophysicists combine seismology, magnetotellurics and measurements of the on-going deformation of the Earth’s surface through GPS and satellite radar data to see what’s underground. Schultz’s focus on the Yellowstone caldera is part of a larger project, the magnetotelluric component (also known as EMScope) of the National Science Foundation’s EarthScope Program.

Topography of Yellowstone-Snake River Plan study area (see inset map for location within the United States), with physiographic provinces outlined in red. USArray magnetotelluric (MT) site locations used for this study are marked with blue dots; 32 sites from the earlier Snake River Plain profiles are denoted by green dots. Smaller gray dots indicate heat flow from an earlier study by Pollack et al. (1991), ranging from 0 (white) to >300 mW/m2 (black) (Figure courtesy of Amna Kelbert; Source: Kelbert A., Egbert G.D., deGroot-Hedlin C. 2012. “Crust and upper mantle electrical conductivity beneath the Yellowstone Hotspot Track” Geology, v. 40, p. 447-450, doi:10.1130/G32655.1)

Schultz, a former program director for the NSF, heads EMScope. In the quest to understand more about the history of the North American continent, EarthScope makes seismic, GPS and MT surveys of the United States and part of Canada. EMScope provides the geomagnetic facet of the survey, producing 3-D images of Earth’s electrical conductivity variations beneath the continent.

Sweeping west to east, scientists are deploying portable arrays of magnetometers and electric field sensors in plastic boxes buried a foot or two in the ground. These small devices silently collect data over a period of one to three weeks, depending on the level of solar storm activity, which provides the source of their signal. Remarkably, the stream of charged particles emitted from the Sun’s atmosphere, the “Solar Wind,” is what makes this all happen. Some of those particles are captured by the Earth’s magnetic field and form gigantic electric currents that flow above the atmosphere, the most famous of which are the aurora (the Northern and Southern Lights). These currents cause other electric currents to flow inside the Earth’s crust and mantle, generating a signal that is detectable by MT devices.

Ancient Rift Revealed

Schultz first encountered geophysics at Brown University in 1979 when MT systems and computers were the size of travel trailers. Instruments today are small, rugged and more mobile. Teams of scientists are currently creating 3D images of the electrical conductivity beneath the comparatively flat landscape of the Midwest. Early results already reveal a billion-year-old ancient rift down the center of the continent, a feature hidden by vast seas of crops and flattened by millions of years of erosion. Magnetotellurics provides a view that goes below the region’s apparent horizon-to-horizon uniformity.

In Oregon, Schultz also leads a magnetotelluric study contributing to the potential geothermal development of Newberry Volcano just south of Bend. Nearly 20 times larger than Mount St. Helens, Newberry is Oregon’s largest volcano. Its flanks slope so gently that it’s hardly visible from any roadside viewpoint. In fact, the city of Bend sits close to the northern flank. The volcano isn’t dead, however. Massive amounts of heat lie just beneath the surface, a potentially large source of alternative energy waiting to be utilized.

The U.S. Department of Energy’s National Energy Technology Lab (NETL) has contracted with Oregon State to monitor and assist in the development of a geothermal system on the caldera’s western rim. AltaRock, a geothermal energy company, aims to demonstrate that sufficient heat can be harnessed from deep beneath the surface. It might be possible to generate electricity at commercially competitive levels. To do so, technicians begin by injecting cold fluids at high pressure into the cracks and crevices in the blistering but otherwise dry basalt underground. Ultimately, those heated fluids could then be extracted to create steam and drive electric turbines to generate power.

Unfortunately, water changes the rock to clay, creating a slimy obstacle that would block the cracks and shut off the water flow back to the surface. However, the fluids also change conductivity, and this property allows geophysicists like Schultz to make 3-D surveys that help identify clogs in the plumbing and keep the water flowing and creating steam.

There’s even a future for magnetotellurics in ocean-wave energy. Turbine buoys used in wave-energy projects generate electromagnetic fields. Since some marine species may be sensitive to electric and magnetic fields, the turbines could potentially disrupt marine ecosystems. To ensure the safety of these fragile areas, Schultz and his team are developing new sensors to gather electromagnetic, seismic and other data. The latest sensor, affectionately called Beaver 1 by the National Geoelectromagnetic Facility, Schultz’s lab, is destined for the ocean floor beneath wave turbines off the Oregon coast.

Continental Collision

Back at Yellowstone, data from MT surveys offer evidence of a more complex explanation for the heat beneath the world’s first national park. While the EMScope sensors have moved on to other areas, early results show the melted remains beneath and to the west of the giant volcano. They whisper of a subducted past. Over 200 million years ago, the Farallon plate, the ancient piece of crust between the North American and Pacific tectonic plates, began to dive beneath young North America. Geologists have known for some time that rather than angling steeply toward the mantle, the Farallon hugged the base of the continent all the way to the current Rocky Mountains. About 16 million years ago, interactions between the diving plate and a mantle plume began forming the volcanic features of the Snake River Plain and Yellowstone before eventually descending to be recycled. All that’s left of the Farallon, mere slivers of its past size, grinds today beneath the coast of North and Central America. Off the Pacific Northwest coast, those remains are called the Juan de Fuca plate.

Geoscientists are still debating what the MT data mean for the evolution of the continent and for specific areas such as Yellowstone. Kelbert, Egbert and Schultz plan to refine their understanding with more magnetotelluric studies of the crust in higher resolution. EMScope is only a first step in 3-D geomagnetic surveys, and the discovery beneath Yellowstone is only a chapter of a complex history. This young science will undoubtedly illuminate more untold stories that lie beneath our feet. Geophysicists will have their hands full for years to come.

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Amanda Enbysk is a senior in the College of Earth, Ocean, and Atmospheric Sciences.

The article contains an account of work sponsored by the Department of Energy and the National Science Foundation, both agencies of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed therein do not necessarily state or reflect those of the United States Government or any agency thereof.

Desert terrain north of Bishop, California (Photo: Bureau of Land Management)

I remember my first day at what’s called “baby field camp” in the Oregon State geology program. Outside Bishop, California, we mapped the area around a cinder cone, long since dead. I quickly learned that the hot sun is a never-ending force of nature, not to be underestimated. I drank at least a gallon of water every day. Professor Andrew Meigs gave me and two-dozen other students our task: Use the tools provided (field notebook, Brunton compass, rock hammer, hand lens and a contour map) to understand what happened to this brick-red hill in the middle of the desert.

Stepping over cacti (sit at your peril!) and even shards of obsidian from long-ago residents, I began training my eyes to notice important clues: the downward dip of cinder layers on the hill, the change in sediment and bedrock colors over distance. I used to overlook these subtle signs, but as I worked, they became critical. The rock hammer clanking on my belt and the hand lens hanging around my neck got me closer to small details, while my legs carried me around the landscape to understand the big picture. Above all, every observation from sediment color, rock composition and how far a layer inclined from horizontal had to be recorded in the orange field book and marked on the contour map.

The maps we created became the key to unraveling the cinder cone’s story. They enabled us to see a cross-section of the Earth under our feet, as though we had sliced down with an enormous knife and peeled the crust back to reveal its ancient face. We started to understand the Earth in three dimensions. We began to appreciate maps for what they are, our connection to the world beyond what we can experience directly through our five senses.

Those ten days in the Southern California desert opened my eyes. I learned how to challenge assumptions and drop expectations before coming to a conclusion about the history of a landscape, all through mapping. Above all, I learned that maps allow us to step back and gain perspective, illuminating patterns that we couldn’t see otherwise. The connections we make with maps produce solutions to some of our most pressing issues and even inspire discoveries. In more ways than one, maps provide a path through the unfamiliar, a priceless tool in such a dynamic world.

This love of maps shouldn’t be surprising for a budding geologist like me. Geology owes much of its existence to maps. In fact, the first geological map was created by a scientist who was intrigued by the coal seams of southeastern England. William Smith, a forefather of modern geology, developed the first geological map. He traveled on horseback, weighed down carriages with rock samples, meticulously wrote and re-wrote and deduced an explanation for the location, orientation and relative age of coal seams and strange figured stones (fossils) that no one understood.

Google Earth provided satellite images on which these axial data reveal the N-S alignment in three ruminant species: (A) Cattle. (B) Roe deer. (C) Red deer. Each pair of dots (located on opposite sites within the unit circle) represents the direction of the axial mean vector of the animals' body position at one locality. (From Begall, et al, 2008, PNAS, Magnetic alignment in grazing and resting cattle and deer)

With his map, Smith brought a deeper understanding to the beautiful countryside so often admired in British culture. He showed that it has a history, a story different than that of biblical origin, the prevailing explanation for the landscape at the time. His studies directly created the science of stratigraphy, the study of rock layers, and with it the rest of geology. Above all, he demonstrated the amazing power of connection and the power of perspective that maps provide.

Today, old maps seem almost quaint. We have Google Earth, which led to one of my favorite discoveries, one involving cows. Researchers used satellite images from Google Earth to survey the orientation of cows and roe deer as they bedded down in locations around the world. The scientists found that, when these animals graze or rest, they tend to line up with magnetic north. This was unknown before the study. Map technology demonstrated an unseen biological property: the behavior of some animals correlates with the lines of force in the Earth’s magnetic field. This connection opens up myriad questions about familiar animals that I thought I understood. It also raises questions about what the Earth’s magnetic field does to the human species. Can it influence our biology? If so, how?

Map of Late Cretaceous coastline (85Ma). (Image from Paleogeography and Geologic Evolution of North America)

Maps even shed light on social and cultural head-scratchers. In the southern United States, there’s a peculiar ribbon of counties across Alabama, Georgia and South Carolina that tend to vote Democratic in presidential elections. Prior to the 1965 Voting Rights Act, this pattern didn’t exist. Most black people did not vote. When researchers overlaid a geological map on the 2000, 2004 and 2008 county-by-county voting census, an intriguing picture came to light. During the Cretaceous Period (145-65 million years ago), the area to become Alabama, Georgia, and South Carolina occupied the coastline of a tropical sea. Warm, shallow waters rich in organic material lapped the shore. The life and death of unfathomable numbers of plankton and other marine organisms produced vast deposits of chalk, which formed the basis for the cotton industry that boomed in America 65 million years later. After the end of voter discrimination nearly 50 years ago, the Democratic leanings of the black voters in this belt became apparent. Who knew that 100-million-year-old geologic history could affect voting patterns today?

Blue counties voted Democratic in the 2008 presidential election (Map: New York Times)

At the “baby field camp” in Southern California, we spent our last five days in a section called Poleta, high in the White Mountains. Trying to understand the gnarled, folded and faulted landscape beyond the first deceptive rise brought many of us to tears. I traced contacts (the boundaries between different rock types) over and over, drawing them where I thought they laid on the map. Eventually, it was necessary to hike out away from the folded hills to hypothesize what might have happened. I remember walking over the last hill, having a rough idea of my conclusions, only to find another fault that changed my thinking.

The sheer frustration of the exercise demonstrated another important point: Maps are hard. They force us to look with a different perspective, to ask tough questions and seek unexpected answers. But what else can we expect from a tool designed to both show and push boundaries?

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Amanda Enbysk is a senior in the College of Earth, Ocean, and Atmospheric Sciences.

Oregon State professor Scott Ashford visited Chile after its February 2010 earthquake.

We’re overdue. If the Cascadia subduction zone behaves as it has in the past, an 8.0 to 8.5 earthquake and a resulting tsunami have a good chance of striking the Pacific Northwest in the next 50 years. That’s the take-home message from OSU marine geologist Chris Goldfinger’s studies of offshore debris flows. He has identified up to 38 such events in the last 10,000 years. At the April 2010 meeting of the Seismological Society of America in Portland, Voice of America correspondent Tom Banse talked with Goldfinger and University of Washington emeritus geophysicist Steve Malone about predicting the next Big One. Read Banse’s account here.

As science defines what’s at stake, what can we do? Oregon Sea Grant’s Pat Corcoran offers tsunami preparedness advice here. Meanwhile, engineers at OSU’s Hinsdale Wave Lab are testing a proposed tsunami evacuation structure for the City of Cannon Beach. Hinsdale engineers previously evaluated the consequences of a tsunami striking Cannon Beach’s neighbor, the City of Seaside. See a video of those tests here and an Oregon Sea Grant video about how research is improving disaster planning for coastal communities.

The New York Times featured a thoughtful op-ed on earthquake engineering on March 27 by Peter Yanev, author of Peace of Mind in Earthquake Country. And if you really want to delve into the faults under the Pacific Northwest, read OSU emeritus geologist Robert Yeats’ book Living with Earthquakes in the Pacific Northwest. You can order it here.

As an undergraduate, Ajeet Johnson (left) worked with Andrew Meigs to study the ages of fault lines. Research, says Meigs, requires students to think differently. “If I tell you that something is one way, you’re not supposed to nod your head and say ‘yes.’ You’re supposed to say, ‘why do you know that?’” (Photo: Conner Burke)

Skiing and rock climbing just weren’t enough. Growing up in Central Oregon’s spectacular landscape, Ajeet Johnson challenged the backcountry of the Cascades. She pulled herself hand-over-hand up Smith Rock and carved down slopes at Mt. Bachelor, but over time, she became curious about the forces that shaped the terrain and will influence its future.

Over the last four years, Johnson has gone from jamming her boots into toeholds and plowing through deep powder to mapping data and measuring fault lines. She received scholarship support for her research and graduated with a bachelor’s in geosciences from Oregon State University last summer. Today, she is pursuing her master’s at OSU.

Her wonderment at the origins of mountains has morphed into a question that has concerned geologists for decades: Why does the expanding Basin and Range region of the American West – one of the most geologically active in the continental United States – come to an abrupt end in the area east of Bend known as the High Lava Plains?

The answers could have implications for Central Oregon’s future. Population has grown faster (73 percent between 1995 and 2007) here than in any other part of the state. The area has seen more than 75 volcanic events over the past 10,000 years, and while the region’s unusual geology provides a source of geothermal energy, it also poses a continuing risk of earthquakes. South of Bend, cinder cones and the 17-square-mile-wide Newberry Crater are reminders of a violent past.

Johnson has focused her research on the Brothers Fault Zone, a complex of relatively young, one- to 10-kilometer-long cracks in the Earth’s surface that run from near Bend toward southern Idaho. Conventional wisdom among geologists is that the age of a fault relates to its length and the differences in height (what geologists call “displacement”) of adjacent terrain. The problem is that, east of Bend, ancient lava flows cover hundreds of square miles, obscuring faults and complicating analysis of their ages.

In 2007, Johnson started measuring fault lines, distinguishing between those that are partially buried and those that are not. She measured the elevations of hundreds of points along the tops and bottoms of slopes. Using a geographic information system, she analyzed data to see if a standard method would yield ages that were consistent with other evidence.

She received support for her research from the Mark W. Chambers Undergraduate Research Grant in the Department of Geosciences and from the Undergraduate Research, Innovation, Scholarship and Creativity fund in the OSU Office of Research.

In a March 2008 presentation at a Geological Society of America meeting in Las Vegas, Nevada, Johnson reported her findings. In short, her analysis showed two results. For faults that cut across rocks older than 7 million years, growth is revealed by the length and height of the fault scarp, or adjacent slope. Faults that cut younger rocks, however, do not show this relationship. Linking among faults and burial of the landscape by lava flows obscure the fault topography.

For her master’s research, Johnson plans to continue studying the forces at work under Central Oregon. Questions remain, she says, about this transition zone between the Basin and Range to the south and the Yakima Folds to the north on the Columbia River Plateau. “The Basin and Range is spreading and is thought to be pivoting from a point in Eastern Washington or Idaho,” says Johnson. “What we’re learning is important for the growing population here and for educating our future scientists.”

The next time you sip a glass of spring water, consider this: Before it got to your lips, that water was soaking through soil, creeping along basalt crevices or flowing through porous volcanic rock. It nurtured microbes, carried dissolved minerals and may have spread the byproducts of human activities. Its pivotal role in the environment has made groundwater a headline topic in human health, waste management and water supplies for growing communities.

One number — 924 million — indicates how vital groundwater is to Oregon. That’s the number of gallons that the U.S. Geological Survey estimates were pumped from Oregon’s aquifers on an average day in 2000. More than 80 percent went to agriculture, most for irrigation.

Large as that number is, it barely begins to tell the story. It is in the subsurface — difficult to see or measure — where the groundwater drama unfolds, and where water availability and purity are subject to the vagaries of geology. Here, uncertainty is a fact of life. And that’s where OSU mathematicians are focusing their efforts to improve the models — equations translated into software code — that help water managers predict the behavior of this unseen resource.

“We really don’t know what’s in the subsurface, and we never will know,” says Malgorzata Peszynska, associate professor in the Department of Mathematics. “You can run seismic waves through it and get a relative idea of how one layer is related to another layer. You can drill observation wells and collect data, but you still don’t know.”

Born and raised in Warsaw, Poland, Peszynska has been working to improve subsurface models for almost two decades. Her love of math goes back to her youth. Undaunted by the teacher who told her there was no future in mathematics for a woman, she received a Ph.D. in the subject at the University of Augsburg in Germany. Her dissertation focused on mathematical techniques for describing liquid flow through porous materials.

In 1994, an invitation to work with one of the field’s leading lights, Jim Douglas Jr. at Purdue, brought her to the United States. Before joining the OSU math department in 2003, she conducted research with Mary F. Wheeler at one of the nation’s leading centers for subsurface modeling, the Institute for Computational Engineering and Science at the University of Texas.

Now, with grants from the U.S. Department of Energy and the National Science Foundation, she is working with students, postdoctoral researcher Son-Young Yi and co-principle investigator and math department chair Ralph Showalter to refine mathematical methods and develop new approaches for simulating groundwater flow.

The researchers are focusing on numerical and computer models. It goes without saying that these sets of equations are complex. They include terms for the velocity of water movement, the porosity and permeability of rock layers and the pressure exerted by water percolating into an aquifer from mountain ridges and other high places.

By simulating water flow through these systems, models can provide insight into how much water is available for human uses and other purposes, but complexity carries a cost. It can add days or weeks to computing time, even on today’s fast computers, such as OSU’s 73-dual-processor SWARM machine in the School of Electrical Engineering and Computer Science.

So the research team’s goal is to develop techniques that can achieve higher accuracy and run in less time. One approach is to simplify details that, in the final analysis, are marginal. That is, they don’t make the model significantly more accurate. The result is what researchers call an “upscaled” model.

“For example,” Peszynska says, “in fractured materials (bedrock), we know there are periodic structures separating blocks of clay (or other impervious materials). Instead of trying to simulate the flow at this scale, we try to come up with an upscaled model of this kind of phenomenon.” The goal is a solution that is close to the original model but does not require as much computational power.

Another goal is to link models that operate at one level — water movement through sand grains, for example — to those that work over a broader scale, such as an entire watershed from mountain ridge to valley floor.

“The use of models that are suitable for laboratory experiments to describe processes on the scale of a watershed will bring any computer to its knees,” says Showalter. “We’re trying to connect information at the microscale to the big picture, and for that we need new mathematical systems that at least give the computers a chance.”

Other OSU faculty members are working on related problems. In the Department of Civil, Construction and Environmental Engineering, Dorthe Wildenschild conducts experiments to understand how fluids behave in the spaces between sand grains. She and Ph.D. student Mark Porter use high-performance X-ray tomography at the Argonne National Laboratory in Illinois to see how air mixes with drops of oil and water in such tight quarters. The speed of these interactions is a critical factor in treating groundwater contaminated by toxic chemicals.

Meanwhile, the speed of model simulation is a factor in the research. “We fly out to Chicago and do the pore-scale experiments in three to four days,” says Wildenschild. “It takes Porter several months to run an equivalent simulation at that small scale on the high-performance computer (SWARM) here on campus.”

In the same department, Brian Wood has worked with Peszynska, Showalter, Enrique Thomann and Ed Waymire in math to characterize groundwater flow in porous materials. Wood focuses on the application of upscaling to the subsurface and to engineered porous systems such as chemical reactors, bioreactors in wastewater plants and sand filters used to clean drinking water. Wildenschild, Wood and other OSU engineers are also collaborating with scientists at the Department of Energy’s Pacific Northwest National Lab in Richland, Washington.

The OSU research couldn’t come at a better time. The need for better models is growing, says Michael Campana, a hydrogeologist and director of OSU’s Institute for Water and Watersheds. Officials who manage water supplies in places such as Oregon’s Klamath, Umatilla and Willamette basins, need to predict availability as demand grows and climate conditions change.

Models are useful approximations of the real world, says Campana, but “uncertainty can stem from the data or from imperfections in the model. It’s a real problem, and it’s getting worse. People are using models to look further into the future. Water managers are increasingly asking what a changing climate will mean for their water resources in 50 years or more. If we give them a number and tell them it could be 30 percent more or less, that’s not good enough.”