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Scientists obtain sharper images of fault lines posing a threat to the Pacific Northwest

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A silent colossus lurks off the Pacific coast, threatening hundreds of miles of coastline with tsunamis and devastating earthquakes.

For decades, scientists have been warning about the possibility of a major fault line breaking off from the Cascadia Subduction Zone, a megathrust fault that runs offshore along the coast from northern Vancouver Island to Cape Mendocino in California. The next time this fault, or parts of it, breaks, it could upend life in Oregon, Washington, and Northern California.

Of particular concern are signs of great earthquakes in the region’s geological history. Many researchers have been pursuing clues about the last “big quake,” a magnitude 8.7 earthquake that occurred in 1700. They have pieced together this history using centuries-old tsunami records, Native American oral histories, physical evidence of saltwater-flooded ghost forests, and limited maps of faults.

But no one had ever comprehensively mapped the fault structure until now. The study published Friday A paper published in the journal Science Advances describes the data collected during a 41-day research voyage, in which the ship dragged a mile-long cable along the fault, listening to the ocean floor and piecing together images.

The team completed a detailed map of the subduction zone, stretching more than 550 miles to the Oregon-California border.

Their work will give modelers a clearer picture of the impact of a megaquake in the region — a megaquake that occurs in a subduction zone, where one plate pushes under another — and give planners a more detailed, localized view of the risks to Pacific Northwest communities, which could help redefine earthquake-resistant building codes.

“It’s like wearing Coke-bottle glasses, and when you take them off, they give you the correct prescription,” said lead author Suzanne Calbott, a marine geophysicist and research professor at Columbia University’s Lamont-Doherty Earth Observatory. “Before, we only got very blurry, low-resolution images.”

Scientists have discovered that subduction zones are much more complex than previously thought. They are divided into four segments, and researchers believe each segment could rupture independently or simultaneously. Each segment has different rock types and different seismic properties, which means some segments may be more hazardous than others.

Earthquake and tsunami modelers are beginning to assess how the new data might affect earthquake scenarios in the Pacific Northwest.

Kelin Wang, a research scientist with the Geological Survey of Canada who was not involved in the study, said her team, which focuses on earthquake hazards and tsunami risk, is already using the data to make predictions.

“The accuracy and resolution is truly unprecedented, and this is an incredible dataset,” said Wang, who is also an adjunct professor at the University of Victoria in British Columbia. “This will allow us to better assess risk and inform building codes and zoning.”

Harold Tobin, co-author of the paper and director of the Pacific Northwest Seismic Network, said the data will help fine-tune predictions, but it won’t change the untenable reality of life in the Pacific Northwest.

“It could potentially produce earthquakes and tsunamis that are comparable in magnitude to the largest earthquakes and tsunamis the Earth has ever seen,” said Tobin, who is also a professor at the University of Washington. “It looks like Cascadia could produce an earthquake of magnitude 9 or a little less or a little more.”

A quake of that magnitude could cause shaking for about five minutes and generate a tsunami up to 80 feet high, damaging more than 500,000 buildings. According to emergency planning documents:.

Neither Oregon nor Washington are adequately prepared.

To map the subduction zone, researchers at sea used active seismic imaging, a technique that sends sound waves into the ocean floor and processes the returning echoes, a method often used in oil and gas exploration.

They towed more than nine miles of cables called streamers behind the ship and used 1,200 hydrophones to capture the returning sounds.

“This will give us an idea of ​​what the conditions are like underground,” Calbot said.

The research vessel Marcus Langes docked in Seattle after a 41-day survey along the Pacific coast that allowed researchers to map the Cascadia Subduction Zone.
Courtesy of Harold Tobin

Trained marine mammal spotters would alert the crew to any signs of whales or other animals. Sounds produced by this type of technology could be disruptive and potentially harmful to marine life.

Calbot said the new research makes it even clearer that the entire Cascadia Fault won’t rupture all at once.

“The next earthquake in Cascadia could rupture just one of these segments, or it could rupture the entire boundary,” Calbot said, adding that some individual segments are thought to have the potential to produce a quake of at least magnitude 8.

Over the past century, scientists have observed only five earthquakes of magnitude 9.0 or higher, all of which were the kind of giant quakes predicted in the Cascadia subduction zone.

Scientists have compiled the latest insights into the 1700 Cascadia earthquake, based on records of an unusual orphan tsunami that was not preceded by any shaking in Japan.

“It would take a magnitude 8.7 earthquake to send a tsunami all the way to Japan,” Tobin said.

Those in Japan who recorded the event had no idea that the earthquake occurred across the ocean in what is now the United States.

Right now, the Cascadia subduction zone is eerily quiet. At other subduction zones, Calbot says, scientists often observe small, frequent earthquakes that make it easier to map the region. But that’s not the case here.

Scientists have a few hypotheses as to why. Wang said the region could be getting quieter as stress builds on the fault, and that time may be approaching.

“The interval between big earthquakes in this subduction zone is about 500 years,” Wang said. “It’s hard to know exactly when it will happen, but it’s certainly quite late compared to other subduction zones.”

Source: www.nbcnews.com

Wildfires are increasingly occurring at night, posing a major challenge

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Recent research suggests that wildfires are no longer subsiding overnight, with their dynamics fueling some of the most extreme and damaging fires.

A study published in the scientific journal Nature indicates that drought is the primary factor causing wildfires to burn during the night. Scientists have observed an increase in the frequency and intensity of overnight fires, a trend they expect to worsen as global temperatures rise due to climate change.

Mike Flanigan, the study author and a professor of wildland fire at Thompson Rivers University in the UK, noted that historically, firefighters used to find relief at night knowing fires typically calmed down. However, this is no longer the case. Fires are now burning hot and intense enough to persist through the night, making firefighting operations riskier and evacuations more complex. Understanding the conditions that lead to nighttime fires can help emergency managers make better decisions in addressing these hazards.

According to Jennifer Balch, an associate professor at the University of Colorado Boulder, the study highlights how climate change is contributing to the increase in wildfires and extreme fire behavior. Researchers have used satellite imagery data to examine over 23,500 fires from 2017 to 2020, identifying a trend where fires can last through the night, particularly in the early stages of large fires. Such fires pose significant risks, especially when they occur at night when people are less prepared.

Balch emphasized that recent wildfires have demonstrated the dangers of nighttime fires, such as the Tubbs Fire in California in 2017 and the McDougal Creek Fire in British Columbia in the Kelowna area. The study also underscores the importance of monitoring drought conditions in predicting overnight fire behavior and assisting emergency responders in proactive decision-making.

The study further emphasizes that human-induced global warming, coupled with expanding communities in fire-prone areas, is putting a strain on firefighting resources and increasing the complexity of managing wildfires. Balch’s research highlights the need to shift towards building fire resilience and acknowledging the challenges faced by firefighters who are continuously battling the escalating threat of wildfires.

Source: www.nbcnews.com

Scientists are using flawed strategies to predict species responses to climate change, posing a dangerous risk of misinformation.

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A new study reveals that a spatiotemporal substitution method used to predict species responses to climate change inaccurately predicts the effects of warming on ponderosa pines. This finding suggests that this method may be unreliable in predicting species’ future responses to changes in climate. Credit: SciTechDaily.com

A new study involving researchers at the University of Arizona suggests that changes are happening faster than trees can adapt. The discovery is a “warning to ecologists” studying climate change.

As the world warms and the climate changes, life will migrate, adapt, or become extinct. For decades, scientists have introduced certain methods to predict how things will happen. seed We will survive this era of great change. But new research suggests that method may be misleading or producing false results.

Flaws in prediction methods revealed

Researchers at the University of Arizona and team members from the U.S. Forest Service and Brown University found that this method (commonly referred to as spatiotemporal replacement) shows how a tree called the ponderosa pine, which is widespread in the western United States, grows. I discovered something that I couldn’t predict accurately. We have actually responded to global warming over the past few decades. This also means that other studies that rely on displacement in space and time may not accurately reflect how species will respond to climate change in coming decades.

The research team collected and measured growth rings of ponderosa pine trees from across the western United States, dating back to 1900, to determine how trees actually grow and how models predict how trees will respond to warming. We compared.

A view of ponderosa and Jeffrey pine forests from Verdi Mountain near Truckee, California.Credit: Daniel Perrette

“We found that substituting time for space produces incorrect predictions in terms of whether the response to warming will be positive or negative,” said study co-author Margaret Evans, an associate professor at the University of Arizona. ” he said. Tree ring laboratory. “With this method, ponderosa pines are supposed to benefit from warming, but they actually suffer from warming. This is dangerously misleading.”

Their research results were published on December 18th. Proceedings of the National Academy of Sciences. Daniel Perrette, a U.S. Forest Service ORISE fellow, is the lead author and received training in tree-ring analysis through the university’s summer field methods course at the University of Arizona Research Institute. The study was part of his doctoral dissertation at Brown University, and was conducted with Dov Sachs, professor of biogeography and biodiversity and co-author of the paper.

Inaccuracies in space and time substitutions

This is how space and time permutation works. All species occupy a range of favorable climatic conditions. Scientists believe that individuals growing at the hottest end of their range could serve as an example of what will happen to populations in cooler locations in a warmer future.

The research team found that ponderosa pine trees grow at a faster rate in warmer locations. Therefore, under the spatial and temporal displacement paradigm, this suggests that the situation should improve as the climate warms at the cold end of the distribution.

“But the tree-ring data doesn’t show that,” Evans said.

However, when the researchers used tree rings to assess how individual trees responded to changes in temperature, they found that ponderosa was consistently negatively affected by temperature fluctuations.

“If it’s a warmer-than-average year, they’re going to have smaller-than-average growth rings, so warming is actually bad for them, and that’s true everywhere,” she says.

The researchers believe this may be happening because trees are unable to adapt quickly enough to a rapidly changing climate.

An individual tree and all its growth rings are a record of that particular tree’s genetics exposed to different climatic conditions from one year to the next, Evans said. But how a species responds as a whole is the result of a slow pace of evolutionary adaptation to the average conditions in a particular location that are different from those elsewhere. Similar to evolution, the movement of trees that are better adapted to changing temperatures could save species, but climate change is happening too quickly, Evans said.

Rainfall effects and final thoughts

Beyond temperature, the researchers also looked at how trees responded to rainfall. They confirmed that, even across time and space, more water is better.

“These spatially-based predictions are really dangerous because spatial patterns reflect the end point after a long period in which species have had the opportunity to evolve, disperse, and ultimately sort themselves across the landscape. Because we do,” Evans said. “But that’s not how climate change works. Unfortunately, trees are in a situation where they are changing faster than they can adapt and are actually at risk of extinction. This is a warning to ecologists. .”

References: “Species responses to spatial climate change do not predict responses to climate change,” by Daniel L. Perrett, Margaret EK Evans, and Dov F. Sachs, December 18, 2023. Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2304404120

Funding: Brown University Department of Ecology, Evolution, and Organismal Biology, Brown Institute for the Environment and Society, American Philosophical Society Lewis and Clark Expeditionary and Field Research Fund, Department of Agriculture Forest Service Pacific Northwest Research Station, Department of Energy Oak Ridge Science Institute Education , NSF Macrosystems Biology

Source: scitechdaily.com