This story was published as a three part series at King5.com. The full un-edited version of the story appears below but we encourage you to read the edited three part series at King5.com.
Read Part 1: Research shakes up seismic knowledge near Northwest nuclear plant
Read Part 2: Seismic concerns under Hanford came long before Japan quake
Read Part 3: Preparing Hanford for a major earthquake
Another version of this story ran in High Country News.
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***full story***
Brian Sherrod's a professional fault finder.
The United States Geological Survey paleoseismologist scrambles up a shrub-covered hillside outside Yakima, WA, points a few hundred yards away and describes how a long stretch of slightly off-colored soil could change perceptions of an entire region's earthquake readiness.
Three years from now, when the latest iterations of the USGS's national hazard maps appear, they'll likely include new information about the Yakima Fold and Thrust Belt. That's a crinkled landscape of anticlines and synclines – hill-like folds of the earth's crust – spread across Central and Eastern Washington, including the spot where Sherrod now stands and, further east, the home of the Northwest's only commercial nuclear reactor.
A new paper by Sherrod and Richard Blakely accepted for publication May 2 highlights compelling new evidence that the Yakima Fold and Thrust belt may be much more seismically active than ling thought. If true, these findings could reshape assumptions used in assessments of nuclear safety, just as regulators try to reassess the controversial energy source in the wake of the March 11 Tohoku earthquake in Japan.
The magnitude 9 Tohoku quake wreaked unfathomable havoc in that country. Buildings collapsed. The ground split and a furious ocean stormed the coast, overwhelming defenses. Roiling, flaming seas of debris marched across cities and farms and deep down river valleys, upending houses and decimating one of the most advanced nations in the world.
Barely before the Japanese could grieve, the sight of smoke at the Fukushima Daiichi nuclear plant stoked new concerns. Soon, news of hydrogen explosions and lost power and overheating fuel rods emerged. Emergency responders pumped seawater in a seemingly quixotic attempt to prevent a radioactive release. Officials declared and expanded evacuation zones. The one country that perhaps most viscerally understood the power of the atom found itself haunted by it again.
Overheated debate
Fukushima's shadow stretched across the Pacific as anti-nuclear activists and industry proponents alike quickly mobilized.
Attention almost immediately turned to the Pacific Northwest, where the Cascadia Subduction Zone has in the past and could again produce quakes similar to what struck Japan.
Nervous thoughts also wandered to a tumbleweed-strewn compound known as the Hanford Site hundreds of miles inland, where nearly six decades ago, as part of the Manhattan Project, it provided the plutonium used in the bomb dropped on Nagasaki, Japan. Throughout the cold war, experiments on Uranium and other elements were conducted at Hanford, where nine nuclear reactors produced plutonium for weapons. Operated by the U.S. Department of Energy, the nearly 600-square-mile Hanford Site is now North America's most contaminated place. A massive cleanup there will last years.
The region also hosts the Columbia Generating Station, which provides 1,150 MW of electricity on land at Hanford leased from the DOE. A joint operating authority known as Energy Northwest and consisting of 27 member public utilities districts from across Washington runs the plant (Once known as the Washington State Public Power Supply System – WPPSS, or “Whoops” as the public often joked – changed its name to Energy Northwest in 1999 to distance itself from a massive municipal bond default that left additional reactors unfinished).
Industry leaders and regulators alike tried to reassure Americans that nuclear power plants across the U.S. are safe.
“At the moment, based on all the information we have, we are convinced that all the plants that are operating in the United States are operating safely,” Nuclear Regulatory Commission spokesman Victor Dricks said.
After sustained public and political pressure, on April 1 the NRC convened a task force to examine nuclear safety.
“We're conducting a 90-day review of the safety of all of the nuclear plants in the country in response to the events in Japan; a quick look to determine if there are things that we need to do, actions we need to take and things we see there,” Dricks said. “ Later, when we've had a chance to thoroughly review all the lessons we learned from Fukushima, we will conduct another review.”
Meanwhile, the commission continues ongoing reviews of plant licenses, including Energy Northwest's application to extend the Columbia Generating Station's operating license to 2043 (the plant's current license expires in 2023). Two plants – Indian Point in New York and Palo Verde in Arizona – have been re-licensed after the events at Fukushima.
[Energy Northwest board members listen during an April 27 meeting to CEO Mark Reddeman summarize the Fukushima disaster and its implications for the Columbia Generating Station.]
So far, the Columbia Generating Station's license application has proceeded smoothly, with a draft environmental impact statement from the NRC scheduled in June. However, NRC letters sent as part of the licensing process reveal the NRC had multiple questions for Energy Northwest about the assumptions it used to develop its response plan for potential accidents. Among the questions: Why did Energy Northwest continue to use 15-year-old studies as the basis for its earthquake preparations, when much more up-to-date information about the region's seismic profile were available from the USGS and Hanford itself?
Meanwhile, two months after the Tohoku quake, NRC staff stymied an effort by a coalition of citizens' groups who want the commission to suspend other activities until it fully reviews lessons learned from the disaster. On May 2, NRC staff recommended that the commission deny the group's emergency petition.
As a plant currently under review, the Columbia Generating Station became one of the petition's focuses. The document said Portland, OR-based Northwest Environmental Advocates was “extremely concerned” about the implications of the Fukushima crisis
“They are particularly concerned about the implications of the Fukushima accident in light of earthquake risks to the Columbia Generating Station based on new findings of a structural zone that kinematically connects faults in central Washington with faults in the Puget Sound, the entirety of which may be seismically active,” the petition said. “The Fukushima accident also highlights the hazards associated with facility mismanagement, which has been a chronic problem at the Columbia Generating Station.”
According to Sherrod, who's not involved with the petition, the findings it refers to are the same ones from his and Blakely's paper.
Though the field is dynamic and growing, Dricks says in-house seismic experts are up to speed on earthquake data and research. Seismic and other hazards are too important only to deal with during plant licensing, Dricks says.
“All of the nuclear plants in the country are required to have designs that address and take into account the most severe natural environmental hazards that have occurred in the area,” Dricks said. After considering the worst case scenario, the commission then adds in a margin of error to its requirements of plant operators to account for unforeseen circumstances. The commission also studies historical data to determine hazards. If new data suggests inadequacies in the existing design of an NRC-regulated plant, the commission and the licensee analyze whether additional action is necessary. If the task force now reviewing nuclear plant safety has any recommendations to change current severe accident mitigation alternatives, or SAMA, reviews, then that could impact NRC's review of Columbia's license, Dricks says.
Meanwhile, the commission pays attention to current operating conditions at nuclear plants across the world.
“We're always looking for information that can be applied to all U.S. reactors, and we analyze information that could become available from any incident, including Japan,” Dricks said. He said the 90-day review launched after Fukushima is looking at all aspects of NRC activities and will provide any lessons learned from the disaster. If there are recommendations
NWEA Executive Director Nina Bell said her organization's concern isn't limited to earthquakes, or any single risk at the Columbia Generating Station. Rather, she said, Fukushima, illustrates that natural disasters can combine with human error, poor siting, inadequate design and operational mistakes into cascading problems.
“Northwest Environmental Advocates believes that nuclear power is inherently an experimental technology and that there are any number of unforeseen triggering actions that are likely to take place,” Bell said
Bell, who said it was “shocking” that the NRC issued Vermont Yankee's new license so soon after the Fukushima event, said the public's being left out of important decision-making by a public body, though she's not surprised by the NRC staff recommendation to deny the petition
“Since the Nuclear Regulatory Commission seeks to the extent possible to eliminate public involvement in its licensing proceedings, the reaction by the NRC staff is, indeed, not a surprise,” Bell said. “At the same time, it is still rather amazing that this huge nuclear accident in Japan is continuing, we still don’t know all of the cascading failures that occurred, and the NRC staff is taking the position that, essentially, we in the United States have nothing substantial to learn from that accident.”
On the case
[USGS paleoseismologist Brian Sherrod in the Wenas Valley, part of the Yakima Fold and Thrust belt. Sherrod suspects previously undiscovered faults exist in this and other parts of the region.]
Rattling along a dirt road in his Silverado pickup, Sherrod describes features of the Wenas Valley that together tell a bigger story. He wants to know whether a scarp – a linear ridge that often indicates sudden shifts in the earth, often, but not always, from earthquakes – indicates an active fault, as he suspects. At first appearing a blur of scrub grass and shrubs, as Sherrod points out exposed basalt and deformations and slight differences in color, the scarp comes into view like one of those 3D images in a Magic Eye poster. The feature's not new to geologists, but Sherrod believes that if he can dig a trench into it he'll find more evidence of an active fault and take a step closer to describing a tectonic region far more seismically active and interconnected than once thought.
In a sense, Sherrod, a member of the Pacific Northwest Seismic Network, is a detective looking for clues of past tremors, and the faults responsible for them.
“I go around and try to identify where active faults are, and try to figure how active they are – in other words, how often earthquakes occur on these faults and how big these earthquakes are,” Sherrod said.
Everything – fossils, layers of sediment, the exacting detail of data from airborne Lidar mapping and magnetometers and, of course, lots of digging in the dirt – helps Sherrod solve the case. Clues might include different types of rocks on each side of a scarp or depositions known as colluvium that form when soil that should be on an upper layer shows up further below, suggesting that an earthquake rearranged the layers.
“The more we work over there, the more we're trying to fit this into a larger tectonic framework,” Sherrod said of his scrutiny of the Yakima Fold and Thrust Belt.
In just the last three years alone Sherrod and his colleagues have found evidence for what are likely three newly-recognized active faults around Yakima, and even more elsewhere in the state.
“I haven't tallied it up, but I'm pretty close to finding a new active fault every year here in Washington,” Sherrod says. He believes he'd find more if only given the resources to go look for them. “It takes money, it takes time, it takes people.”
[The slight indentation in the center of the rise in the center of this photo is a scarp indicating a possible fault in the Wenas Valley, just south of Untanum Ridge, near Yakima, WA.]
One retired geologist deeply familiar with the Yakima Fold and Thrust Belt is intrigued by the study.
“We may have structures here that are actually more active than what we thought in the past, “ said Steve Reidel, who was a Hanford geologist for 30 years and now teaches at Washington State University, Tri-Cities.
The author of “Big Black Boring Rock,” a book about Northwestern geology, Reidel said fault records are difficult to find because scarps are rare, thanks to a different sort of cataclysm: The Missoula Floods. “Only” about 15,000 years ago, the bursting of an ice dam on a glacial lake released huge volumes of water, then over the next 2500 years, did so about 40 times more. The floods were so forceful that they buried scarps and washed out features that might have been the best evidence of faults.
Reidel says that's why it's so crucial that geologists be given the resources to trench suspect faults – even most young faults would still be older than the Missoula Floods – so they can dig beneath the surface, beyond where key evidence may have been washed away.
“The problem is how do you get funding to do it?” Reidel asked. “We did it on weekends and evenings. As a couple of my friends said, our wives funded our research.”
Now, Reidel says, data collection that was always low key until Sherrod, Blakely, and others tarted exploring links across the Cascades, is changing the minds of people like himself.
“The way I look at it, we're just at the cusp of that knowledge base now,” he says. “My attitude and ideas of what's going on over here are changing based very much on what they did, but we don't know what it all means and we don't know how significant the young faulting, because we've never really had a chance to trench some of the features.”
Even if previously unknown faults are found, that won't mean a huge earthquake is coming tomorrow, but it also won't mean there's no chance of a temblor. What it will mean is better tools with which to evaluate safety of places like Hanford and the Columbia Generating Station. It also doesn't mean Reidel will leave town any time soon.
“The west coast is particularly dangerous [for earthquakes], but the best way to look at it is the probability of a big earthquake is the same every day and it's pretty small,” Reidel says. “Some day you're going to have that earthquake. You don't know when, but you're going to have it, but it's still a small risk every day.”
Old Models
Questions about the Columbia Generating Stations's safety didn't start with Fukushima. Last fall the AP reported that the industry-funded Institute of Nuclear Power Operations said the plant was one of two in the nation most in need of improvement . In 2009, the plant had five unplanned shutdowns – known as “scrams” – Seattle's King 5 TV station reported in April.
Energy Northwest officials refused requests for interviews for this story, but three days after the Tohoku quake, company officials assured a jittery public that the Columbia Generating Station was well prepared for the unlikely event of natural disaster, thanks to redundant backup power systems, a safe distance from the Columbia River in case the upriver Grand Coulee Dam bursts, and engineering that would help the plant weather ground shaking exceeding what would come from the largest earthquake expected in their region.
[Energy Northwest CEO Mark Reddeman]
Later in March, Energy Northwest CEO Mark Reddeman penned a widely-circulated op-ed further detailing the plant's preparations and meant to counter public apprehensions about nuclear power.
“In the past weeks, too much misinformation about nuclear energy has played on people's fears,” Reddeman wrote. “The anti-nuclear lobby has seen an opportunity and they are exploiting it.”
In the op-ed, Reddeman said this wasn't the time to debate the merits of developing additional nuclear power resources in the U.S. Rather, he wrote, the nuclear industry will thoroughly study in minute-by-minute detail to incorporate lessons learned once the situation at Fukushima stabilizes and can be studied.
“What you should know - and may know already - is that your friends and neighbors who work at Columbia Generating Station have an unwavering dedication to safety,” Reddeman wrote.
On March 10, only a day before the Tohoku quake, Energy Northwest received the latest in a series of letters from the NRC questioning the sufficiency of calculations the company used to inform its cost-benefit analysis of earthquake impact mitigations. A July 1 2010 letter, meanwhile, reveals NRC's concern that Energy Northwest used old seismic hazard analyses to measure ground-shaking, despite more recent studies of earthquake hazards, like ones done by the USGS or the Pacific Northwest National Laboratory for projects related to the cleanup effort at nearby Hanford.
The NRC's Dricks said these letters only seek to clarify technical details and don't cast doubt on plant safety.
“There is no reason for people living near the plant to fear for their safety,” Dricks said in an email.
Dricks later said that Energy Northwest's response to the March 10 letter, as well as some unanswered questions from the July, 2010 letter, is due May 9.
Energy Northwest did respond to the seismic hazards question from that letter in a Sept. 17 response. It told the NRC that the Columbia Generating Station is farther away from seismic sources in the Yakima Folds than the Hanford facilities in question, with different soil structures underneath. Moreover, the response continued, a 2005 study at Hanford suggest that estimates of hazards were similar to what earlier studies had shown, and that data from a 2008 USGS hazard map suggests the company was actually being more conservative than necessary in predicting ground motion.
The question will now become whether the next USGS hazard map – scheduled for release in 2014 – will include updated information about hazards in the Yakima Fold and Thrust Belt. That will depend in large part on how much study the Pacific Northwest Seismic Network team is able to do on the region and on what new knowledge research like that done by Sherrod and Blakely brings to the table.
Neighbors
Of course, shifting knowledge about the Yakima Fold and Thrust belt doesn't just have direct implications for the Columbia Generating Station. As separate as the Columbia Generating Station and the Hanford Site may be from a management and oversight standpoint, the fact remains that the two are inextricably linked, if for no other reason but geography.
What happens, for example, if the World War II era “Canyon” buildings where uranium was processed collapse? What if the K-basins that store fuel from Hanford's old N-Reactor leak? What if a radioactive release at Hanford hampers responders' ability to address a crisis at the Columbia Generating Station?
Eric Holdeman, an emergency management consultant who previously worked at the Washington State Division of Emergency Management, says there's a proximity challenge for the Columbia Generating Station.
“When you have hazards in proximity to one another, everybody is doing their own thing, but it would be interesting to know to what degree they've looked at their 360 degree view, not from natural hazards but technological hazards,” Holdeman, who writes the “Disaster Zone” blog, said. Typically, he said, disasters like the one in Japan aren't single events, but multiple events that together cause worse problems to occur. “I've just lived long enough to know never say never.”
Even given the risk of unexpected events, there's only so much that can be done about major infrastructure.
“Once a facility like a nuclear power plant is built, it's built,” Holdeman said. “You might be able to do something with the backup power, but the containment vessel is the containment vessel, it is what it is.”
Ivan Wong, a board member at the Earthquake Engineering Research Institute says the seismic hazard in Eastern Washington has probably been underestimated.
“Seismology and geology and this whole business of earthquake hazards is not a perfect science, so as we learn more about earthquake processes and earthquake hazards we have to go back and revisit what we've done in the past,” Wong said.
Each earthquake brings new information that contributes to our understanding of risks, Wong said. Regulatory agencies keep tabs on scientific developments as they evolve. Critical structures like power plants are either safe from newly discovered risks, or they're forced by regulators to retrofit, he said, and therefore the public can feel confident in their safety.
Room for new work
[A seismometer at the Columbia River Exhibition of History, Science & Technology in Richland, WA]
There are significant fears elsewhere in the Northwest.
The Cascadia Subduction Zone – which stretches approximately from Northern California to Vancouver, British Columbia – will someday, possibly soon, unleash a quake similar to the one in Japan. The Northwest is less prepared for a subduction quake than was Japan or Chile, where another subduction quake struck in February, 2010, but such an event probably wouldn't cause heavy damage in the Tri-Cities.
Nevertheless the Tri-Cities aren't completely safe.
One of Washington's largest documented quakes hit in 1872. Geologists are still trying to pinpoint exactly how big it was, or where it was centered, but it's widely believed to have been a 6.8 temblor with an epicenter near the south end of Lake Chelan, perhaps as far south as the town of Entiat. That's about 100 miles from the Columbia Generating Station.
It's also unclear what sources inform Energy Northwest's assessments of the Columbia Generating Station's risks, since its probablistic safety assessments still refer to a 1994 study, long before much of the current research and data came together.
To be sure, the Columbia Generating Station based its design specifications on the far larger quake near Lake Chelan. Another significant large quake in the region was the 1936 shaker near Milton-Freewater, in Oregon. These quakes are still quite recent from a geological perspective, and the monitoring now in place at Hanford only reveals so much about the record.
In fact, there just isn't much seismic data from the region surrounding the Columbia Generating Station. The first seismic monitors were installed at Hanford in 1969. The largest quake they've ever recorded was a 3.8 (the most recent quake detected in the region was a magnitude 3.3 shaker just east of Hanford on April 29), but that doesn't mean a larger quake can't occur.
“The 20 to 30 years we've been monitoring is a very short time,” says the USGS geophysicist Joan Gromberg.
In the 1970s, some of the first significant work at Hanford to support a planned Basalt Waste Isolation Project became the first detailed look at the region's tectonics. That meant working on mapping the region's faults and folds, work that continued until 1989, when the DOE abandoned the project to focus on a proposed nuclear repository at Yucca Mountain, Nevada. Afterword the only data collected was seismicity, which helps provide information about how much the ground shakes or may shake but doesn't give a sense of the long-term frequency or history of earthquakes.
When Reidel, who came to Hanford to work on the Basalt project, and Al Rohay, who managed the Hanford Seismic Assessment Program for the DOE until the task was transferred to a Hanford Contractor this month, wanted to trench Rattlesnake Mountain, a more than 3,000 foot high treeless mountain that dominates the Horizon, they couldn't secure funding. Without the DOE building anything new, there wasn't a justification to study potential faults any further.
[Located at Hanford, Rattlesnake Mountain, one of the largest treeless mountains in the world, dominates the view throughout the Tri-Cities and is a prominent feature of the Yakima Fold and Thrust Belt.]
“Out of all the industrialized countries, the U.S. has the least amount of geologic mapping done, which is kind of a sad state of affairs,” Reidel said.
Sherrod says his and his colleagues' ability to map the state's seismic risks is limited only by the amount of resources the federal government is willing to throw their way, not by a lack of subjects to study. They just need the time, funding and other help necessary to collect and sift through data.
The more data they collect, the more geologists will be able to shift a raging debate about the Columbia Plateau and the Yakima Fold and Thrust Belt: Whether these regions thin- or thick-skinned.
Thick-skinners think that deformations in the Columbia River Basalts cut deep into the seismogenic – or earthquake producing – part of the earth's crust, and can thus cause larger earthquakes. Thin skin adherents say a structure known as a “decollement” – essentially flat faults where layers of rock slide across one another and bunch up into rises similar to the way a rug pushed across a floor might – shaped the Yakima Folds as it slid between the basalts and the crystalline basement.
Sherrod says his newly accepted paper puts forth a thick-skin model and that he and his colleagues have the data to support that hypothesis. But that doesn't mean geologists have enough data about the region.
“I have thought for a long time there is just a general lack of knowledge about active faults in Central Washington,” Sherrod said. “There's a lot of room for new work.”
People like Sherrod and Blakely might be finding the big faults, determining how frequently earthquakes occur on them and understanding how big they can be. There's still one question they can't answer.
“When's the next big one going to be?” Sherrod says. “That's the one we always get. We just don't know.”
Sidebar One: Plutonium Pride
[Atomic Ale & Eatery General Manager and Brewmaster Dave Acton]
For decades, the Hanford site drove the economy of nearby Richland – essentially a company town for the nuclear industry – and, to a lesser extent, Kennewick and Pasco, Richland's neighbors in a metropolitan area known as the Tri-Cities. Now the cleanup continues to define the region; commanding large portions of 2009 stimulus funds and keeping the Tri-Cities economy afloat as the Great Recession hit the rest of the Northwest hard.
All of this reinforces a sense of “plutonium pride.” All over the Tri-Cities are landmarks like Atomic Laundry and Proton Lane. Student athletes at Richland High School play for the Bombers. Their mascots are mushroom clouds.
“We're proud of the cloud," says Dave Acton, a Richland native.
Over pints of Plutonium Porter, Richland native Dave Acton – the general manager and brewmaster at Atomic Ale & Eatery – describes his hometown pride. Easily mistakable for Jeff Bridges's title character from “The Big Lebowski,” Acton rolls his eyes at nuclear fears.
At the confluence of the Yakima, Snake and Columbia Rivers, two other cities besides Richland comprise the Tri-Cities. Pasco is a rail town that's become a magnet for Latino immigrants. Panaderias, taquerias and predominantly Spanish signage fill the city's business district. In a city that's also the gateway to Eastern Washington's grain farms, Pasco's outdoor farmer's market is one of the state's biggest. To the south, meanwhile, Kennewick is the region's shopping hub, with both an indoor shopping mall and a sprawl of arterials lined with big boxes and strip malls, while bars, tattoo parlors and headshops – as well as a number of wood furniture refinishers – now dominate the city's older Downtown.
[The Snake and Yakima Rivers meet the Columbia near Washington's Tri Cities.]
The surrounding region is largely agrarian. Volcanic soil from the Columbia River Basalts makes the hills and valleys of the Yakima Fold and Thrust Belt prime wine country. Combined with pleasant weather and a resilient economy, the Tri-Cities have grown faster than other parts of the Northwest.
“There's a lot of people in this area, but they're not from here,” Acton said. “People sold their cracker boxes in Seattle or California for 3 or 4 million dollars, came here and bought a mansion on the mountainside. Then they come in and they say 'oh my god, this area is dangerous.'"
Acton's fed up with newcomers who try to whitewash the region's history by suggesting that the high school change its mascot, for example.
“Quit trying to change our area,” Acton said. “You moved here. We are who we are.”
Acton says he doesn't take Richland's nuclear history as a negative. He says the city has a reason to be proud. Those who came to work on the Manhattan Project are no different than shipbuilders who built the USS Enterprise, or the women who inspired Rosie the Riveter and helped build B-17s and Mustangs.
“Here in Richland we didn't necessarily ask to be in the war, we didn't necessarily want to be in the war, but we can say with complete and utmost certainty that we ended that thing,” Acton said. “It's not about deaths, it's not about destruction, it's 'let's get this done, so we can all get along now for a change.' Unfortunately, we never will.”
Now, Acton said, nuclear power is a way of turning the knowledge gained in the pursuit of nuclear weapons back into something useful He dismisses concerns as fear-mongering.
“Panic sells,” Acton says. “Peace doesn't.”Sidebar Two: Tearing Down the Wall
Until recently, geologists and geophysicists believed that the young volcanoes of the Cascade Range separated everything to their west from everything to their east. In their new paper, Blakely and Sherrod tear down that wall.
“Now we're looking at the Cascades as a mountain system,” Sherrod said. He sees himself in a faction of scientists that theorizes that – from the Snoqualmie Pass South – the Cascades are only five million years old, or younger (some volcanologists put their “birth” tens of millions of years before that). That would mean they might have formed after a 10 to 15 million year long period when lava oozed across 63,000 square miles of the Northwest. Those lava flows formed the Columbia River Flood Basalts, one of the largest such flows in the world and a defining feature of the Northwest.
Many subtle clues support this position. One is part of the Pacific Northwest experience: The “rain shadow” caused by the Cascades, for example, which block moisture from passing from the Pacific Ocean to eastern Oregon and Washington. With wet wetter in one side of the Cascades but not the other, you'd expect different vegetation, as is the case today. The Columbia River Basalts, however, contain fossils of wet-weather vegetation you might find in the Great Smoky Mountains, suggesting that the Cascades weren't there to block rainfall when the basalts formed.
Over the last decade, the USGS mapped faults around the Puget Sound area west of the Cascades to identify hazards in the heavily populated area. As they did, they found fault systems that seem to link up with faults deep in the basalts of the Yakima Fold and Thrust belt. Previously, most geologists thought the Cascade Volcanoes separated the Pacific Northwest into two different tectonic regions. Knowing that the basalts existed before the volcanoes means it's likelier that the two sides are connected and part of a larger, deeper fault system than previously thought, not isolated features. That doesn't mean that all the faults will rupture at the same time if one does, but it does show a more complex interaction of seismic stresses than once taught.
“You have to view this as a whole, a whole system. you can't just kinda look at things in one little piece in isolation,” says Joan Gromberg, a geophysicist who works with Sherrod.
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