The University of Michigan is at the forefront of a collaboration aimed at better predicting the chain reactions of downstream damage triggered by wildfires, hurricanes, earthquakes, and more.
After the flames of the Southern California wildfires in January were brought under control, residents understood that threats still lingered.
The fires had set the stage for mudslides on some of L.A.’s hillsides as February’s rains descended. These mudslides can alter the terrain in ways that introduce new hazards, such as obstructing drainage routes and increasing future flooding risks.
“These hazards do not function as standalone, isolated events,” stated Marin Clark, a professor of earth and environmental sciences at the University of Michigan. “The initial event triggers a series of related hazardous occurrences.”
These chains can be observed across the full range of disasters, from fires in California and dam failures in Michigan to hurricanes moving inland into Appalachia. However, the interconnectedness of nature and our engineered environments typically becomes evident only after they start affecting one another.
That is why Clark and a group of colleagues from across the nation are striving to enhance our capability to comprehend and foresee these linked, or cascading, hazards, as outlined in a recent paper published in the journal Science.
“Our understanding has significantly advanced in just the past decade, following significant incidents—fires, earthquakes, hurricanes,” Clark mentioned. “These occurrences have generated valuable data sets and prompted new thinking about how we can integrate these processes to anticipate future hazardous conditions.”
Clark also serves as the primary investigator for the Center for Land Surface Hazards Catalyst, or CLaSH, a project backed by the National Science Foundation designed to expedite this essential work. CLaSH began as what is referred to as an NSF Center Catalyst, a prototype center aimed at consolidating a group of experts to spearhead transformative research in critical scientific areas important for the nation.
Mitigating the effects of surface hazards stands as a national priority, highlighted by the National Landslide Preparedness Act of 2021, which was reauthorized in 2024. In contrast to the significant events that reshape landscapes, the interconnected hazards left in their aftermath are often underexplored, leaving society more susceptible to their risks, according to Clark. Thus, scientists have a crucial role in assisting the nation in addressing this gap.
“While federal and state agencies are tasked with minimizing disaster-related losses, we currently lack an academic research community in the U.S. dedicated to fundamental research,” Clark remarked. “This foundational research is vital for effective disaster response and for training a future workforce equipped to meet the increasing demand for resilience against natural hazards. Such resilience is crucial for safety and economic advancement.”
That is the rationale behind the establishment of the CLaSH Catalyst and why its members, including Clark and lead author Brian Yanites from Indiana University, have published the new report in Science. The group is setting the stage to develop the tools, methodologies, and workforce needed to bolster resilience to the downstream impacts of disasters, potentially saving lives and billions of dollars in damage.
A call to action
“I vividly remember the Tuesday before Hurricane Helene made landfall,” shared Yanites, an assistant professor of earth and atmospheric sciences at Indiana University. “I sent an email to the research team involved with this new national center, foreseeing, ‘This is going to be detrimental to southern Appalachia.’
Yanites and his team had been researching the area and understood the hurricane had the potential to incite additional events. However, understanding the possibilities is distinct from accurately predicting what is likely to transpire. That’s the objective researchers are aiming for, yet the field is still developing.
“We began monitoring the situation Tuesday night, aware that there would be numerous landslides and flooding,” Yanites commented. “However, we lack the scientific tools to definitively state, ‘How many landslides will occur? Where will they manifest? What consequences will arise for downstream processes and effects?’”
Such events can also have prolonged repercussions, noted Josh West, a professor of earth sciences and environmental studies at the University of Southern California and a co-investigator of CLaSH. The flooding and landslides resulting from such extreme occurrences push sediment and debris into river valleys, obstructing the natural drainage pathway for subsequent rainfall. Consequently, the flooding risk in these regions can remain heightened for years or even decades.
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Beyond the academic world, few individuals consider these interconnected risks, West remarked. However, a center such as CLaSH can assist in enhancing awareness around these matters so that locals and support organizations are better equipped.
“Helene serves as a prime illustration, but events like this occur globally,” West stated. “These consequences linger for years, manifesting in unexpected ways.”
This contrasts somewhat with the wildfires in California and their associated risks, which West studies as well. The fires occur with such regularity that residents instinctively understand the increased likelihood of mudslides during the following winter rains.
Nonetheless, there remains potential for enhancement and fresh insights that initiatives like CLaSH can provide. Recent studies have indicated that the behavior of soil in scorched regions regarding water repulsion or absorption is not as straightforward as previously assumed.
“On one hand, you might call that a minor detail,” West noted. “Conversely, it’s critical to accurately grasp such particulars if we wish to comprehend and predict these sequences of hazards in the future.”
During its catalyst phase, CLaSH began uniting specialists from diverse fields to incorporate new viewpoints into how researchers uncover and analyze these details—and how they aggregate to create the enduring hazard cascade. By nurturing this platform, the CLaSH team aspires to connect foundational and applied research communities to strengthen the nation’s resilience against cascading hazards.
“We’ve already observed this during the catalyst phase; the whole is indeed greater than the sum of its parts,” West expressed. “The research community hasn’t experienced anything like this before, and there’s considerable enthusiasm surrounding it.”
Community-Level Impact
Another factor complicating this research is that the various scales of differing hazards and their downstream effects do not fit neatly within a single research domain, mentioned Dimitrios Zekkos, co-author of the Science study and CLaSH co-investigator. In his area of civil and environmental engineering, for instance, people excel at ensuring the safety of individual structures against specific threats.
“We can design a building to withstand an earthquake, but what about the larger community? What about essential services like roads, energy, water, and everything else involved in daily living? Will there be other cascading events such as fires and landslides?” Zekkos, a professor at the University of California Berkeley, questioned. “Being secure in my own building is insufficient. Community resilience is lacking.”
Uniting a broad array of experts studying hazards and their interdependencies across various scales is crucial to tackling this challenge. So far, CLaSH has collaborated with over 600 researchers.
Technological advancements have also proven invaluable for researchers tackling cascading hazards at the community level. The advent of drones and robotics, along with enhancements in remote sensing technologies from satellites, enables researchers to observe more locations with greater detail. They can swiftly investigate areas after a disaster while also elucidating the pre-existing conditions.
“What we’re witnessing now with drones, satellites, and related technologies was unimaginable just five years ago,” Zekkos reflected.
These instruments are generating vast amounts of new data, which, in turn, assist experts in creating improved computer models. These models can cover entire regions, aiding communities in predicting and preparing for cascading hazards.
Making the advantages of these tools, data, and models more accessible to a wider range of communities across the U.S. is a long-term objective for CLaSH, and significant progress is already underway. The endeavors of Josh Roering, professor of earth sciences at the University of Oregon and CLaSH co-investigator, exemplify this goal.
His team investigates various issues, including debris flows that pose a risk in steep mountainous terrains, such as Klukwan in southeastern Alaska, where fieldwork is conducted. Here, rocks and soil frequently tumble down steep slopes into catchments, accumulating until released by rainfall and melting snow. The resultant flows can be catastrophic.
“Debris flows resemble floods, but instead of just water, they encompass boulders, trees, and other materials that can cause significant destruction,” explained Roering, who also co-authored the Science report.
The Alaska Native community in Klukwan has coexisted with these flows for generations. They have essentially built their community on land formed from the deposits of these flows. However, circumstances are evolving.
Western building and infrastructure practices have been adopted, and atmospheric rivers are inducing more intense precipitation, while rising temperatures are impacting the permafrost layers that stabilize the rocks from which debris flows originate.
Roering and his team have been collaborating with Klukwan’s Indigenous community to better prepare for the changing risks posed by these flows through monitoring tools and mitigation strategies, such as constructing berms.
“We’re already making significant progress together, but continuing our partnership with CLaSH would enable us to escalate our efforts and enhance everything we’re doing,” he stated. “It would elevate our work to a higher level.”
The CLaSH Catalyst has united a network of researchers to collaboratively tackle these challenges more effectively and efficiently than they could alone. Now, maintaining and expanding this cooperation could yield actionable results for real-world communities at a faster pace.
“I believe that’s what makes our work distinctive and significant,” Clark remarked. “This isn’t something one researcher can accomplish alone. We genuinely require the skills and perspectives of a diverse array of scientists from various disciplines.”
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