Strata

By Nancy Steinberg
Fall/Winter 2023

When her mother came to the Oregon coast for a visit, Felicia Olmeta-Schult felt it was only right to explain what to do in the case of an earthquake or tsunami. After all, she knew that the risk of such hazards hangs in the air in Oregon all the time, thanks to the usually-quiet Cascadia Subduction Zone where one tectonic plate dives beneath another. It’s also Olmeta-Schult’s job to teach people about such hazards, as she is Oregon Sea Grant’s coastal hazards specialist. But this new information scared her mom a little.

“It brought her some anxiety,” Olmeta-Schult recalls. “When she was driving on Highway 101 and saw the ‘Entering a tsunami zone’ signs, she was holding her breath.”

Felicia Olmeta-Schult

Olmeta-Schult knows the feeling. “Often people just freeze when there is an earthquake. They don’t know what to do. It happened to me in a mini-earthquake in California before I had this job. I was washing dishes, I felt the earthquake, and I just froze.”

One antidote to this fear and inaction is more knowledge. The College of Earth, Ocean, and Atmospheric Sciences is leading the way in understanding geohazards such as earthquakes and volcanic eruptions in the Pacific Northwest, and in preparing communities for these events. These efforts are all tied together by an emphasis on collaboration and communication, including among scientific teams working on interconnected aspects of earthquake dynamics and with community groups to improve resilience.

Synthesizing and filling holes in our knowledge

A critical first step in seeking to understand the hazards themselves is a new cross-disciplinary, cross-institutional initiative focused on the Cascadia Subduction Zone. Dubbed CRESCENT, for Cascadia Region Earthquake Science Center, this collaboration will be led by scientists at University of Oregon and will include Pieter-Ewald Share, Andrew Meigs and Anne Tréhu of CEOAS. CRESCENT, funded by the U.S. National Science Foundation at $15 million over five years, has a three-pronged structure. The program’s roughly three dozen researchers will focus on foundational science, workforce development, and application and partnerships to increase resiliency of regional communities to the risks these hazards present.

Why a regional research center? Share emphasizes the importance of tying disparate scientific threads together. “We are working with a complex, dynamic, interconnected tectonic system where all the parts are incompletely understood,” he says. “The only way to holistically understand this system is to bring the Earth science community and their data and products together, and synthesize everything in a self-consistent manner. Progress on this front is extremely difficult otherwise.”

Share notes that it is critical to understand this particular system, an active subduction zone. “If you look at subduction zones around the world, they produce the biggest earthquakes, there’s no question,” he says. “And then there are all these cascading effects, beyond the earthquake itself. You have the potential for landslides, tsunamis, even fires. With our steep slopes and abundant rains, we could experience liquefaction [when the shaking of the Earth causes soils to lose their strength and therefore their ability to support structures].”

These compounded risks weigh on Share. “It’s a very important problem,” he says, “And there are some devastating side effects to getting it wrong.”

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The only way to holistically understand this system is to bring the Earth science community and their data and products together

-Pieter-Ewald Share

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The research conducted by CRESCENT scientists will fill gaps in our knowledge, including quantifying the stress building up in the Cascadia system; determining where that stress might be relieved by identifying the weakest points, or faults, along the tectonic plate boundaries; mapping those faults throughout the system; determining what has happened at those faults when they have slipped in the past; and using information like the composition and densities of the materials in and around the faults to determine how much shaking will take place when they do rupture.

Will all of this information lead us to the holy grail of earthquake prediction? That’s not currently the primary goal, Share explains. “There are no universally observed or accepted earthquake precursors that are predictive,” he says. For this reason and several others, “The earthquake science community has moved away from ‘predicting’ and more toward ‘forecasting,’ putting a future big earthquake in probabilistic instead of deterministic terms.”

“The hazard of major faults in southern California, for example, are now spoken of in terms of percentages in number of years — for example, a particular fault section might have a 10% probability of earthquake rupture in the next 30 years,” he says.

Another hazard: volcanoes

While the Cascadia Subduction Zone is perhaps best known as the potential source for large earthquakes and resulting tsunamis, it also is the reason we have so many volcanoes in the Pacific Northwest, which present serious risks as well (see figure on p. 14). The 1980 eruption of Mount Saint Helens reminds us that the volcanoes in the Cascadia arc are considered active. Share says that while the initial focus of CRESCENT will be on earthquakes, the project will also shed light on regional volcanic activity.

Adam Kent, CEOAS geologist and an associate dean, points out that forecasting is perhaps different for volcanoes compared to earthquakes, in part because there are more pre-eruption signals. “The thing about a volcano is typically, although not always, you get a much longer precursory phase. If Mount Hood was going to erupt, we’d probably have weeks or months of recognizable signs, like seismic signals, changes in gasses emitted, changes in temperature in the hot springs, maybe changes in the shape of the volcano.” It’s a good thing that Mount Hood will likely throw these signs, as Kent explains that Hood is considered one of the top volcanic threats in the country.

Adam Kent

But forecasting volcanic eruptions is still no easy task. Volcanoes work via many invisible processes that we are only beginning to understand on a larger scale. “If I think about volcanoes, there are gaps all over the place in our understanding of the pretty dramatic physical and chemical processes happening about 10 kilometers below us, completely out of sight. So, we can only really tell what’s going on by looking at either the remote record, or by looking at what happened last time,” Kent says.

Kent adds that another confounding variable in our understanding of volcanoes is climate change. Shifts in precipitation patterns and groundwater hydrology could theoretically change certain eruptions called phreatic events. These eruptions happen when hot magma comes in contact with groundwater, creating a near-instant explosion as the trapped water expands and turns to steam. “If you change the hydrology near a volcano, we might expect changes to these kinds of eruptions in terms of frequency or severity,” Kent says. The melting of glaciers off of the flanks of volcanoes as the Earth’s temperatures rise might also change eruption frequency. Recent CEOAS research spearheaded by paleoclimatologist Alan Mix found that during the last ice age, 18,000 years ago, the rapid melting of ice covering volcanoes in western North America was associated with increased volcanic activity.

“Ice cover to volcanoes is like a cork in a champagne bottle. Remove the icy cork and boom, the eruptions begin,” Mix says.

Community preparedness is key

CRESCENT will work with Felicia Olmeta-Schult and others to ensure that the latest science is translated into life-saving community education. She says that community preparedness for geohazards depends on many factors, including the type of hazard and where you live. Answering basic questions is a good starting point. These include, Is my home, school or work in a tsunami zone? If so, what is the safest evacuation route for me? Becoming informed is a vital first step to building community-wide resilience, she says.

Disaster preparedness and response become even more challenging when layered with language and cultural complexities. Olmeta-Schult has been working on a project under the umbrella of the Cascadia Coastline and Peoples Hazards Research Hub, or Cascadia CoPes Hub, headquartered at CEOAS, to ensure preparedness among Latina/o/x communities on the Oregon Coast. She starts by trying to identify and address the daily challenges of marginalized and underserved communities (language barriers, access to resources) during what she calls “blue sky” days so they can be better prepared on the inevitable “gray sky” days when emergencies occur. The project’s multi-pronged approach has resulted in increased awareness in the community and, interestingly, among the project’s personnel as well.

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It’s important for people to know they’re not alone … in a neighborhood where people already do things like potlucks together, we are asking, how can we build on that?

-Felicia Olmeta-Schult

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For example, the group recently worked with Spanish-speaking communities in Seaside and Astoria. “We did a little training on map literacy. We have all these maps about tsunami zones and evacuation routes, but we realized that people don’t really use maps anymore,” Olmeta- Schult says “Especially if English is not your first language, the maps can be really disorienting. When you ask people to look at the map and say, ‘Where is your home? Where is the school?’ It takes a little while to figure that out. We’re exploring the idea of making accurate but simpler maps, which might contain photos or icons.”

In the end, it’s critical to strike a balance between empowering people and overwhelming them. Olmeta-Schult works towards this sweet spot by helping people understand the little things they can do in their own lives to improve resilience, and by focusing on ways that people can work together in times of crisis. “It’s important for people to know they are not alone. For example, in a neighborhood where people already do things like potlucks together, we are asking, how can we build on that?”

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The Cascadia Subduction Zone is a place where two of Earth’s tectonic plates meet, moving towards each other at a rate of about a half an inch per year. As the oceanic Juan de Fuca Plate is pushed beneath (subducted under) the North American Plate, it sometimes “slips” at shallower depths (marked in red under the Coast Range in the diagram), releasing a lot of built-up pressure at once, causing an earthquake. When the subducting plate descends and heats up it releases fluids which cause the overlying mantle to melt, forming magma. The magma rises to the surface to fuel the volcanoes we know as the Cascades. Image adapted from one created by the U.S. National Park Service.

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It’s all about connections

All of the efforts to understand and prepare for Cascadia disasters come down to community collaboration. This emphasis on community is obvious in Olmeta-Schult’s work, but it’s true for Cascadia science as well. Share well recognizes that CRESCENT will operate best by forming and maintaining community. “We’ll be bringing together these diverse groups that usually would be doing great work, but they would be doing it separately. And we’re getting them all into the same room to work on the same complex system of goals, and that’s by far the most exciting part,” he says.

Pieter-Ewald Share

“These connections with engineers, the community, with the workforce, with Indigenous groups … each has its own level of complexity, but as long as we keep working together, I think we’re on the right path.”

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Abby P. Metzger contributed significant research and conceptual and editorial work to this story.

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