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    Study: Heavy snowfall and rain may contribute to some earthquakes

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    When scientists look for an earthquake’s cause, their search often starts underground. As centuries of seismic studies have made clear, it’s the collision of tectonic plates and the movement of subsurface faults and fissures that primarily trigger a temblor.But MIT scientists have now found that certain weather events may also play a role in setting off some quakes.In a study appearing today in Science Advances, the researchers report that episodes of heavy snowfall and rain likely contributed to a swarm of earthquakes over the past several years in northern Japan. The study is the first to show that climate conditions could initiate some quakes.“We see that snowfall and other environmental loading at the surface impacts the stress state underground, and the timing of intense precipitation events is well-correlated with the start of this earthquake swarm,” says study author William Frank, an assistant professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “So, climate obviously has an impact on the response of the solid earth, and part of that response is earthquakes.”The new study focuses on a series of ongoing earthquakes in Japan’s Noto Peninsula. The team discovered that seismic activity in the region is surprisingly synchronized with certain changes in underground pressure, and that those changes are influenced by seasonal patterns of snowfall and precipitation. The scientists suspect that this new connection between quakes and climate may not be unique to Japan and could play a role in shaking up other parts of the world.Looking to the future, they predict that the climate’s influence on earthquakes could be more pronounced with global warming.“If we’re going into a climate that’s changing, with more extreme precipitation events, and we expect a redistribution of water in the atmosphere, oceans, and continents, that will change how the Earth’s crust is loaded,” Frank adds. “That will have an impact for sure, and it’s a link we could further explore.”The study’s lead author is former MIT research associate Qing-Yu Wang (now at Grenoble Alpes University), and also includes EAPS postdoc Xin Cui, Yang Lu of the University of Vienna, Takashi Hirose of Tohoku University, and Kazushige Obara of the University of Tokyo.Seismic speedSince late 2020, hundreds of small earthquakes have shaken up Japan’s Noto Peninsula — a finger of land that curves north from the country’s main island into the Sea of Japan. Unlike a typical earthquake sequence, which begins as a main shock that gives way to a series of aftershocks before dying out, Noto’s seismic activity is an “earthquake swarm” — a pattern of multiple, ongoing quakes with no obvious main shock, or seismic trigger.The MIT team, along with their colleagues in Japan, aimed to spot any patterns in the swarm that would explain the persistent quakes. They started by looking through the Japanese Meteorological Agency’s catalog of earthquakes that provides data on seismic activity throughout the country over time. They focused on quakes in the Noto Peninsula over the last 11 years, during which the region has experienced episodic earthquake activity, including the most recent swarm.With seismic data from the catalog, the team counted the number of seismic events that occurred in the region over time, and found that the timing of quakes prior to 2020 appeared sporadic and unrelated, compared to late 2020, when earthquakes grew more intense and clustered in time, signaling the start of the swarm, with quakes that are correlated in some way.The scientists then looked to a second dataset of seismic measurements taken by monitoring stations over the same 11-year period. Each station continuously records any displacement, or local shaking that occurs. The shaking from one station to another can give scientists an idea of how fast a seismic wave travels between stations. This “seismic velocity” is related to the structure of the Earth through which the seismic wave is traveling. Wang used the station measurements to calculate the seismic velocity between every station in and around Noto over the last 11 years.The researchers generated an evolving picture of seismic velocity beneath the Noto Peninsula and observed a surprising pattern: In 2020, around when the earthquake swarm is thought to have begun, changes in seismic velocity appeared to be synchronized with the seasons.“We then had to explain why we were observing this seasonal variation,” Frank says.Snow pressureThe team wondered whether environmental changes from season to season could influence the underlying structure of the Earth in a way that would set off an earthquake swarm. Specifically, they looked at how seasonal precipitation would affect the underground “pore fluid pressure” — the amount of pressure that fluids in the Earth’s cracks and fissures exert within the bedrock.“When it rains or snows, that adds weight, which increases pore pressure, which allows seismic waves to travel through slower,” Frank explains. “When all that weight is removed, through evaporation or runoff, all of a sudden, that pore pressure decreases and seismic waves are faster.”Wang and Cui developed a hydromechanical model of the Noto Peninsula to simulate the underlying pore pressure over the last 11 years in response to seasonal changes in precipitation. They fed into the model meteorological data from this same period, including measurements of daily snow, rainfall, and sea-level changes. From their model, they were able to track changes in excess pore pressure beneath the Noto Peninsula, before and during the earthquake swarm. They then compared this timeline of evolving pore pressure with their evolving picture of seismic velocity.“We had seismic velocity observations, and we had the model of excess pore pressure, and when we overlapped them, we saw they just fit extremely well,” Frank says.In particular, they found that when they included snowfall data, and especially, extreme snowfall events, the fit between the model and observations was stronger than if they only considered rainfall and other events. In other words, the ongoing earthquake swarm that Noto residents have been experiencing can be explained in part by seasonal precipitation, and particularly, heavy snowfall events.“We can see that the timing of these earthquakes lines up extremely well with multiple times where we see intense snowfall,” Frank says. “It’s well-correlated with earthquake activity. And we think there’s a physical link between the two.”The researchers suspect that heavy snowfall and similar extreme precipitation could play a role in earthquakes elsewhere, though they emphasize that the primary trigger will always originate underground.“When we first want to understand how earthquakes work, we look to plate tectonics, because that is and will always be the number one reason why an earthquake happens,” Frank says. “But, what are the other things that could affect when and how an earthquake happens? That’s when you start to go to second-order controlling factors, and the climate is obviously one of those.”This research was supported, in part, by the National Science Foundation. More

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      in Energy

      Lessons from Fukushima: Prepare for the unlikely

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      When a devastating earthquake and tsunami overwhelmed the protective systems at the Fukushima Dai’ichi nuclear power plant complex in Japan in March 2011, it triggered a sequence of events leading to one of the worst releases of radioactive materials in the world to date. Although nuclear energy is having a revival as a low-emissions energy source to mitigate climate change, the Fukushima accident is still cited as a reason for hesitancy in adopting it.

      A new study synthesizes information from multidisciplinary sources to understand how the Fukushima Dai’ichi disaster unfolded, and points to the importance of mitigation measures and last lines of defense — even against accidents considered highly unlikely. These procedures have received relatively little attention, but they are critical in determining how severe the consequences of a reactor failure will be, the researchers say.

      The researchers note that their synthesis is one of the few attempts to look at data across disciplinary boundaries, including: the physics and engineering of what took place within the plant’s systems, the plant operators’ actions throughout the emergency, actions by emergency responders, the meteorology of radionuclide releases and transport, and the environmental and health consequences documented since the event.

      The study appears in the journal iScience, in an open-access paper by postdoc Ali Ayoub and Professor Haruko Wainwright at MIT, along with others in Switzerland, Japan, and New Mexico.

      Since 2013, Wainwright has been leading the research to integrate all the radiation monitoring data in the Fukushima region into integrated maps. “I was staring at the contamination map for nearly 10 years, wondering what created the main plume extending in the northwest direction, but I could not find exact information,” Wainwright says. “Our study is unique because we started from the consequence, the contamination map, and tried to identify the key factors for the consequence. Other people study the Fukushima accident from the root cause, the tsunami.”

      One thing they found was that while all the operating reactors, units 1, 2, and 3, suffered core meltdowns as a result of the failure of emergency cooling systems, units 1 and 3 — although they did experience hydrogen explosions — did not release as much radiation to the environment because their venting systems essentially worked to relieve pressure inside the containment vessels as intended. But the same system in unit 2 failed badly.

      “People think that the hydrogen explosion or the core meltdown were the worst things, or the major driver of the radiological consequences of the accident,” Wainright says, “but our analysis found that’s not the case.” Much more significant in terms of the radiological release was the failure of the one venting mechanism.

      “There is a pressure-release mechanism that goes through water where a lot of the radionuclides get filtered out,” she explains. That system was effective in units 1 and 3, filtering out more than 90 percent of the radioactive elements before the gas was vented. However, “in unit 2, that pressure release mechanism got stuck, and the operators could not manually open it.” A hydrogen explosion in unit 1 had damaged the pressure relief mechanism of unit 2. This led to a breach of the containment structure and direct, unfiltered venting to the atmosphere, which, according to the new study, was what produced the greatest amount of contamination from the whole weeks-long event.

      Another factor was the timing of the attempt to vent the pressure buildup in the reactor. Guidelines at the time, and to this day in many reactors, specified that no venting should take place until the pressure inside the reactor containment vessel reached a specified threshold, with no regard to the wind directions at the time. In the case of Fukushima, an earlier venting could have dramatically reduced the impact: Much of the release happened when winds were blowing directly inland, but earlier the wind had been blowing offshore.

      “That pressure-release mechanism has not been a major focus of the engineering community,” she says. While there is appropriate attention to measures that prevent a core meltdown in the first place, “this sort of last line of defense has not been the main focus and should get more attention.”

      Wainwright says the study also underlines several successes in the management of the Fukushima accident. Many of the safety systems did work as they were designed. For example, even though the oldest reactor, unit 1, suffered the greatest internal damage, it released little radioactive material. Most people were able to evacuate from the 20-kilometer (12-mile) zone before the largest release happened. The mitigation measures were “somewhat successful,” Wainwright says. But there was tremendous confusion and anger during and after the accident because there were no preparations in place for such an event.

      Much work has focused on ways to prevent the kind of accidents that happened at Fukushima — for example, in the U.S. reactor operators can deploy portable backup power supplies to maintain proper reactor cooling at any reactor site. But the ongoing situation at the Zaporizhzhia nuclear complex in Ukraine, where nuclear safety is challenged by acts of war, demonstrates that despite engineers’ and operators’ best efforts to prevent it, “the totally unexpected could still happen,” Wainwright says.

      “The big-picture message is that we should have equal attention to both prevention and mitigation of accidents,” she says. “This is the essence of resilience, and it applies beyond nuclear power plants to all essential infrastructure of a functioning society, for example, the electric grid, the food and water supply, the transportation sector, etc.”

      One thing the researchers recommend is that in designing evacuation protocols, planners should make more effort to learn from much more frequent disasters such as wildfires and hurricanes. “We think getting more interdisciplinary, transdisciplinary knowledge from other kinds of disasters would be essential,” she says. Most of the emergency response strategies presently in place, she says, were designed in the 1980s and ’90s, and need to be modernized. “Consequences can be mitigated. A nuclear accident does not have to be a catastrophe, as is often portrayed in popular culture,” Wainright says.

      The research team included Giovanni Sansavini at ETH Zurich in Switzerland; Randall Gauntt at Sandia National Laboratories in New Mexico; and Kimiaki Saito at the Japan Atomic Energy Agency. More

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      in Environment

      Preparing to be prepared

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      The Kobe earthquake of 1995 devastated one of Japan’s major cities, leaving over 6,000 people dead while destroying or making unusable hundreds of thousands of structures. It toppled elevated freeway segments, wrecked mass transit systems, and damaged the city’s port capacity.

      “It was a shock to a highly engineered, urban city to have undergone that much destruction,” says Miho Mazereeuw, an associate professor at MIT who specializes in disaster resilience.

      Even in a country like Japan, with advanced engineering, and policies in place to update safety codes, natural forces can overwhelm the built environment.

      “There’s nothing that’s ever guaranteed safe,” says Mazereeuw, an associate professor of architecture and urbanism in MIT’s Department of Architecture and director of the Urban Risk Lab. “We [think that] through technology and engineering we can solve things and fight nature. Whereas it’s really that we’re living with nature. We’re part of this natural ecosystem.”

      That’s why Mazereeuw’s work on disaster resilience focuses on plans, people, and policies, well as technology and design to prepare for the future. In the Urban Risk Lab, which Mazereeuw founded, several projects are based on the design of physical objects, spaces, and software platforms, but many others involve community-level efforts, so that local governments have workable procedures in case of emergency.

      “What we can do for ourselves and each other is have plans in place so that if something does happen, the level of chaos and fear can be reduced and we can all be there to help each other through,” Mazereeuw says. When it comes to disaster preparedness, she adds, “Definitely a lot of it is on the built environment side of things, but a lot of it is also social, making sure that in our communities, we know who would need help, and we have those kinds of relationships beforehand.”

      The Kobe earthquake was a highly influential event for Mazereeuw. She has researched the response to it and has a book coming out about natural disasters, policies, and design in Japan. Beyond that, the Kobe event helped reinforce her sense that when it comes to disaster preparedness, progress can be made many ways. For her research, teaching, and innovative work at the Urban Risk Lab, Mazereeuw was granted tenure at MIT last year.

      Two cultures grappling with nature

      Mazereeuw has one Dutch parent and one Japanese parent, and both cultures helped produce her interest in managing natural forces. On her Dutch side, many family friends were involved with local government and water management — practically an existential issue in a country that sits largely below sea level.

      Mazereeuw’s parents, however, were living in Japan in 1995. And while they happened to be away while the Kobe earthquake hit, her Japanese links helped spur her interest in studying the event and its aftermath.

      “I think that was a wake-up call for me, too, about how we need to plan and design cities to reduce the impact of chaos at the time of disasters,” Mazereeuw says.

      Mazereeuw earned her undergraduate degree from Wesleyan University, majoring in earth and environmental sciences and in studio art. After working in an architectural office in Tokyo, she decided to attend graduate school, receiving her dual masters from Harvard University’s Graduate School of Design, with a thesis about Kobe and disaster readiness. She then worked in architecture offices, including the Office of Metropolitan Architecture in Rotterdam, but returned to academia to work on climate change and disaster resilience.   

      Mazereeuw’s book, “Design Before Disaster,” explores this subject in depth, from urban planning to coastal-safety strategies to community-based design frameworks, and is forthcoming from the University of Virginia Press.

      Since joining the MIT faculty, Mazereeuw has also devoted significant time to the launch and growth of the Urban Risk Lab, an interdisciplinary group working on an array of disaster-preparedness efforts. One such project has seen lab members work with local officials from many places — including Massachusetts, California, Georgia, and Puerto Rico — to add to their own disaster-preparedness planning.

      A plan developed by local officials with community input, Mazereeuw suggests, will likely function better than one produced by, say, consultants from outside a community, as she has seen happen many times: “A report on a dusty shelf isn’t actionable,” she says. “This way it’s a decision-making process by the people involved.”

      In a project based on physical design, the Urban Risk Lab has also been working with the U.S. Federal Emergency Management Agency on an effort to produce temporary postdisaster housing for the OCONUS region (Alaska, Hawaii, and other U.S. overseas territories). The lab’s design, called SEED (Shelter for Emergency Expansion Design), features a house that is compact enough to be shipped anywhere and unfolds on-site, while being sturdy enough to withstand follow-up events such as hurricanes, and durable enough to be incorporated into longer-term housing designs.

      “We felt it had to be really, really good quality, so it would be a resource, rather than something temporary that disintegrates after five years,” Mazereeuw says. “It’s built to be a small safety shelter but also could be part of a permanent house.”

      A grand challenge, and a plethora of projects

      Mazereeuw is also a co-lead of one of the five multiyear projects selected in 2022 to move forward as part of MIT’s Climate Grand Challenges competition. Along with Kerry Emanuel and Paul O’Gorman, of MIT’s Department of Earth, Atmospheric and Planetary Sciences, Mazereeuw will help direct a project advancing climate modeling by quantifying the risk of extreme weather events for specific locations. The idea is to help vulnerable urban centers and other communities prepare for such events.

      The Urban Risk Lab has many other kinds of projects in its portfolio, following Mazereeuw’s own interest in conceptualizing disaster preparedness broadly. In collaboration with officials in Japan, and with support from Google, lab members worked on interactive, real-time flood-mapping software, in which residents can help officials know where local flooding has reached emergency levels. The researchers also created an AI module to prioritize the information.

      “Residents really have the most localized information, which you can’t get from a satellite,” Mazereeuw says. “They’re also the ones who learn about it first, so they have a lot of information that emergency managers can use for their response. The program is really meant to be a conduit between the efforts of emergency managers and residents, so that information flow can go in both directions.”

      Lab members in the past have also mapped the porosity of the MIT campus, another effort that used firsthand knowledge. Additionally, lab members are currently engaging with a university in Chile to design tsunami response strategies; developing a community mapping toolkit for resilience planning in Thailand and Vietnam; and working with Mass Audubon to design interactive furniture for children to learn about ecology.  

      “Everything is tied together with this interest in raising awareness and engaging people,” Mazereeuw says.

      That also describes Mazereeuw’s attitude about participation in the Urban Risk Lab, a highly cross-disciplinary place with members who have gravitated to it from around MIT.

      “Our lab is extremely interdisciplinary,” Mazereeuw says. “We have students coming in from all over, from different parts of campus. We have computer science and engineering students coming into the lab and staying to get their graduate degrees alongside many architecture and planning students.” The lab also has five full-time researchers — Aditya Barve, Larisa Ovalles, Mayank Ojha, Eakapob Huangthananpan, and Saeko Baird — who lead their own projects and research groups.

      What those lab members have in common is a willingness to think proactively about reducing disaster impacts. Being prepared for those events itself requires preparation.

      Even in the design world, Mazereeuw says, “People are reactive. Because something has happened, that’s when they go in to help. But I think we can have a larger impact by anticipating and designing for these issues beforehand.” More