ANTHROPOGENIC SEISMIC NOISE
Lockdown was the longest period of quiet in recorded human history
by Tanya Basu / July 23, 2020
“When lockdown started in March, the world went instantly, strangely silent. City streets emptied. Joggers and families disappeared from parks. Construction projects froze. Stores closed. Now a network of seismic monitoring stations around the world has quantified this unprecedented period of quiet. The resulting research into “seismic silence,” published in Science today, has shown just how much noise we contribute to the environment. It has also let scientists get an unparalleled listen to what’s happening beneath our feet. “We can safely say that in modern seismology, we’ve never seen such a long period of human quiet,” says Raphael De Plaen at the Universidad Nacional Autónoma de México in Querétaro, one of the paper’s 76 authors.
Seismic noise, or vibrations of the earth, is most often associated with earthquakes. But seismology also listens to the interplay of earth and water, tracking things like ocean swells and atmospheric pressure changes. Humans are the third-biggest source of seismic noise. Everyday urban activities like commutes, or stadiums full of fans simultaneously going wild in “football quakes,” are strong enough to register on seismometers. “It’s transport, like cars, trains, traffic, buses,” says coauthor Paula Koelemeijer of the Royal Holloway University of London. “It’s retail and recreation—not just people going shopping, but also going to parks. It’s workplaces and residences.” Under normal circumstances, this human noise merges with and muffles natural seismic activity. Exactly how much our behavior affects the levels of background noise has been hard to work out until now. Lockdown presented a unique opportunity for researchers not only to control for human activity but also to hear seismic noise that otherwise gets drowned out.
The researchers—who included academics and citizen scientists—used data collected from 268 seismic monitoring stations around the world. These devices included highly technical seismographs housed in academic institutions. But about 40% of the data also came from Raspberry Shakes, personal seismographs that are built and used by hobbyists. The group used these devices in tandem with anonymized mobility data collected from Google and Apple to detect human movement. They were then able to match those observations with seismic noise reports in order to figure out whether seismic events were likely to be human-caused or natural. Of the 268 stations, 185, or 69%, showed significant reductions in high-frequency seismic ambient noise, the cocktail of human-produced and natural ambient noise that surrounds us. This silence began in late January in China; by mid-March, it had descended on the world.
While the periods between Christmas and New Year and over Chinese New Year are usually the quietest, the difference was even starker this time. Sri Lanka, for example, saw a 50% reduction in noise, the largest the researchers measured. Sundays in New York’s Central Park are usually lively, but lockdown numbers registered a 10% reduction from the weeks immediately before. Even sensors buried deep under the surface picked up on the sudden lack of human activity above. A German observatory that lies almost 500 feet beneath rock was able to detect a drop in vibrations once lockdown kicked in.
The noise patterns also highlighted human migration. De Plaen says that the Mexico-US border showed an increase in human seismic noise, even though both sides of the border were otherwise still. Citizen seismographs were able to pick up the noticeable drops in noise around schools and universities. The study itself was a product of the pandemic. Lead author Thomas Lecocq, a seismologist at the Royal Observatory of Belgium, had been writing code to better understand how to tease apart human-generated and seismic noise. He and some colleagues had initially exchanged Twitter direct messages and coordinated through WhatsApp groups before creating a Slack group to coordinate their research on April 1. The Slack group—combined with the accessibility of Raspberry Shakes—expanded the data and made it stronger. “It’s not every day that you publish results after less than four months of work,” De Plaen says.
The fall-off in human noise also gave scientists a chance to listen to the earth’s inner workings more closely than ever before—without humans drowning them out. This might add to our knowledge of earthquakes, particularly small ones in urban centers that are often masked by human seismic noise. Smaller earthquakes are key to being able to monitor fault lines, and they act as predictors of bigger quakes to come; scientists now have a baseline data set to work with. “We can [now] study relationships between human activity and seismology,” De Plaen says. “We can now understand with a high level of resolution what is generating noise: the earth or humans.” As we emerge from lockdown, scientists hope this understanding of human-caused noise will also help us better understand how we’re moving and living—just by listening. Not that the human noise ever truly went away. Koelemeijer’s seismograph would spike some mornings, when a neighbor’s washing machine would hit the spin cycle. Even in the depths of the quietest period of human history, “human environments aren’t really ever completely silent,” she says. “You’ll always still pick up some noise.”
As the world quieted down in 2020, Raspberry Shakes listened
by Alka Tripathy-Lang / 12/17/2020
“It’s the trains!” Ryan Hollister yelled to his wife Laura as he burst into their home in Turlock, California. For two weeks in 2017, they’d been staring at data from their newly installed Raspberry Shake, a Raspberry Pi-powered instrument that detects how the ground moves at a specific location. Expecting to see the tell-tale wiggles of distant earthquakes, they instead saw peculiar cigar-shaped waveforms at regular intervals. “The biggest challenge,” says Laura Hollister, “was the noise.” “I thought it was the toilet flushing or the washing machine,” says Ryan Hollister, but simple tests of going to the restroom or doing the laundry proved him wrong. While stuck in his car watching a train rattle through Turlock, he realized the three tracks that criss-cross this small California town could be causing this mystery seismic noise. As soon as he got home, he pulled up the Raspberry Shake’s data. Sure enough, each weirdly intense caterpillar of seismic waves corresponded to a train, with the highest-amplitude waves correlating with the nearest track’s schedule, only a half mile from home.
“The Hollisters’ Raspberry Shake continues to record the cigar-shaped signatures of the trains in Turlock, California, while also capturing far-off earthquakes, like this magnitude-7.4 event from New Zealand on June 18, 2020. The New Zealand quake is highlighted in yellow in the background and enlarged in the inset.”
It wasn’t the last time that their seismic listening device picked up signs of human activity. As COVID-19 engulfed our world, the Hollisters, a husband-wife team of Earth science educators, noticed that their Raspberry Shake registered much lower levels of activity than usual. The drop was pronounced at times when their street, a main artery to the local high school, should have been pulsing with teenagers. That change was far from limited to Turlock. Thomas Lecocq, a seismologist who pays particular attention to Earth’s ubiquitous vibrations, discerned a marked decrease in high-frequency noise on a permanent seismic station under his purview at the Royal Observatory of Belgium. This peculiar hush was quieter and longer than the one he’d seen during the subdued days between Christmas and New Year and coincided with his country’s lockdown. In the following months, Lecocq and 76 coauthors from around the world combed through data from seismic stations spanning more than 70 countries using Python code Lecocq wrote specifically for this purpose. A total of 268 stations had usable data, and 185 of them saw high-frequency seismic noise plummet by up to 50 percent in urban regions. The changes came in lockstep with each country’s closure in response to COVID-19. As the signals from driving, construction, and even walking fell away, Ian Nesbitt, one of Lecocq’s coauthors says, “We may be able to investigate [geologic] signals that we previously couldn’t see because it was masked by that noise.”
“Created in 2016, the Raspberry Shake is a personal seismograph that can detect local to regional earthquakes. The Shake was developed by OSOP, a geophysical instrument company headquartered in Panama. Marketed toward makers and the earthquake-curious, it also has the potential to help professionals increase the station density of seismic monitoring networks.”
Many of the stations were high-end research instruments installed by university or government scientists. But 65 were tiny Raspberry Shakes, sitting in the homes and offices of scientists and hobbyists alike. It turns out that when humans make a lot of noise, seismically speaking, anyone with a spare Raspberry Pi and a few hundred dollars for a Raspberry Shake circuit board and some sensors can see it. The basic recipe for a seismic station requires four ingredients: sensors to measure Earth’s motion, a means to record the measurements, a long-term storage solution (either local or elsewhere), and a power source, says Emily Wolin, Seismic Network Manager for the U.S. Geological Survey (USGS) Albuquerque Seismological Laboratory. State-of-the-art seismic stations boast numerous sensors that detect an immense range of frequencies, capturing Earth’s movement in three directions—up-down, east-west, and north-south. Digitizers and data loggers precisely record and time stamp the data. To power the equipment, the most remote stations may use solar panels, with power requirements varying dramatically based on communication needs, says Wolin.
— Jordi Diaz Cusi (@JDiazCusi) March 30, 2020
To add a new seismic station to an earthquake monitoring network, Wolin says scientists must scout locations that take into account regional geology and possible noise sources—like railroads (the Hollisters’ home would have never made the cut). With a list of candidate sites, they then identify and contact landowners for permission and secure access for construction, installation, and subsequent maintenance. Wolin explains that sometimes, preparation may involve “hiring a drill rig to bore hundreds of meters into solid rock.” In some instances, thermally sealed and waterproof seismic vaults must be carefully constructed to house equipment so sensitive that they would otherwise pick up minuscule changes in pressure and temperature. Vaults also help minimize pesky anthropogenic noise. To install the sensor and electronics, “it’s not rocket science,” says Sue Hough, a USGS seismologist, but “it does take special training.” Each layer of complexity adds another line to the bill. According to Hough, top-tier versions of a seismic station can cost well over $10,000, excluding installation costs. Branden Christensen, CEO of Raspberry Shake, says that when those costs are included, installing a single seismic station could cost upwards of $100,000. Those prices are exclusively affordable to government agencies, research institutions, and industry.
“Old-school (left) versus new-school (right) seismic monitoring at the Hawaiian Volcano Observatory on Kilauea. Kilauea is well monitored, but small seismographs like the Raspberry Shake could densify networks in places that are less well covered.”
Raspberry Shakes, on the other hand, have basic versions of the same components at a fraction of the price. A Raspberry Shake circuit board costs as little as $100, and it plugs into almost any ethernet or wireless-enabled Raspberry Pi. “We thought that people would have [Raspberry Pis] sitting around in their drawers,” says Christensen, “and we [designed Raspberry Shakes to] support them all.” A seismic sensor, like a geophone, plugs into the Raspberry Shake board, which serves as an amplifier and digitizer. The sensor’s output comes in the form of voltage differences that must be amplified and converted into a known voltage per velocity. This conversion, called a gain, leaves the output in voltage units, according to Nesbitt, who is also Raspberry Shake’s former chief scientist. The Raspberry Shake digitizes this information and pipes it to the Raspberry Pi for further processing and archiving. An 8 gigabyte microSD card, which Nesbitt describes as the hard drive of the Raspberry Pi, ships with every Raspberry Shake and comes pre-loaded with all of the Shake software. The Raspberry Pi houses the SD card and provides power for the entire seismic station. “[The Raspberry Pi] is the computer underlying everything,” says Nesbitt.
With a Raspberry Shake board, building your own seismic station from scratch becomes as simple as adding a sensor and plugging the Raspberry Pi into your wall socket, although Christensen recommends crafting an enclosure (you can use Lego bricks!) to protect it from the bumps of the denizens of your household. If you’d rather not assemble your own from scratch, Raspberry Shake makes several turnkey options based on the number and type of sensors you want. Turnkey options, Hough says, pack all these components into a compact plexiglass box. The Hollisters chose the turnkey Raspberry Shake 4D, which can be had for under $400. To install, Ryan Hollister says all they needed to do was, “level it and point the axes in the right direction so it’s oriented properly, and plug it in.” Easy as, well… pi(e). “If you imagine the whole gamut of earthquakes from the really small local ones that happen beneath your feet to the big ones that might happen half a world away,” Christensen says, “[all these earthquakes] are losing their high frequency energy as they move away from the source.” If your instrument is limited to high frequencies, by the time the waves of an earthquake arrive, you might not be able to see them. “Really expensive instruments look at all frequencies,” he continues, “and can see everything from local to regional to worldwide earthquakes.” Raspberry Shakes focus on those higher frequency waves that fade away at great distances, which makes them ideal for detecting local and regional seismic sources, says Nesbitt. However, Shakers (as owners call themselves) can still see waves from earthquakes 10,000 kilometers away, so long as they are at least a magnitude 6.0 event. In fact, Shakers can look at the mobile app, released during lockdown and watch an earthquake roll in, complete with a countdown to the waves’ arrivals.
Every Raspberry Shake, including the most popular Raspberry Shake 1D, comes equipped with a geophone that measures the vertical component of seismic waves. According to Nesbitt, the frequency range detected by these sensors, between 0.5 to 50Hz, neatly brackets anthropogenic noise sources, which run between 5 to 20Hz. Raspberry Shakes, he says, are “perfect for the seismic noise study,” not only because of their ideal frequency range, but also because their owners often live where data from permanent stations may not be available to non-governmental scientists, such as India. For people who care less about the cultural noise and more about big local earthquakes, Wolin cautions that geophones will saturate in the event of shaking strong enough to feel—the waves will be larger than the detector can register. “You can actually hear this,” says Wolin. “If you pick up your Raspberry Shake and shake it up and down [simulating the jolts of a large earthquake], you can hear the geophone hitting the top and bottom of the case”—it can’t move any farther than that. To measure violent shakes that can throw you into the air, Nesbitt says that accelerometers, like the sensors that rotate the screen of your smartphone, can stay on scale during shaking up to several times Earth’s gravitational acceleration. Unfortunately, accelerometers fail to measure small ground motions because they produce a high amount of background noise; they only measure what people can feel, says Nesbitt. Raspberry Shake solves this problem by combining a vertical-component geophone with accelerometers in the Raspberry Shake 4D. For people who live in earthquake country, “you cover all the bases with the same little box,” Hough says.
Our staff is teleworking. The earth continues shaking. Ground movements at frequencies 1-20 Hz, mainly due to human activity (cars, trains, industries,…) are much lower since the implementation of the containment measures by the government. #StayHome @ibzbe @CrisiscenterBE pic.twitter.com/pGgQAyLuUP
— Seismologie.be (@Seismologie_be) March 20, 2020
Considering Raspberry Shake’s price-point, how do these petite instruments compare to their more expensive counterparts? The answer—surprisingly well. In 2019, scientists at the USGS Albuquerque Seismological Laboratory determined that Raspberry Shakes, though designed for hobbyists, are among low-cost sensors that can enhance existing seismic networks. This may be especially useful in seismically active countries with limited budgets. The ability to strengthen an existing network without needing to spend $10,000 and up per station could be the beginning of a revolution in seismology, says Hough. Adding more stations to an existing network directly enhances Earthquake Early Warning efforts, where denser networks ensure rapid detection of earthquakes. Wolin, who coauthored the USGS study, says their testing confirmed that the instruments meet manufacturers’ specifications and that the geophones record regional earthquakes well enough. However, she says, “Scientific users need to be conscious of [Raspberry Shakes’] limitations, and not expect them to perform to the same specifications as typical research-grade seismic equipment.” “There will always be a place for stations that can record everything the ground is doing,” says Hough. Nevertheless, she says, “though a low-cost sensor can’t do everything… they can do an awful lot, especially for practical applications.”
“Comparison between seismic data from high-end seismometers versus a Raspberry Shake-4D. The Raspberry Shake appears to lag by about 10 milliseconds, a trivial amount to hobbyists but significant for researchers.”
To guarantee rapid, seamless integration of Raspberry Shakes into existing seismic networks, all of them produce output in seismology’s standard format, miniSEED, a stripped-down version of SEED, the Standard for the Exchange of Earthquake Data. This step happens in real time on the Raspberry Pi. According to Nesbitt, “The miniSEED files are broken up by day… but all that data is encoded to miniSEED on the fly.” This data is archived on the microSD card in real time and, if the hardware is connected to the Internet, can be shared via Raspberry Shake’s data center. Collectively, Shakers have made more than 30 terabytes of data from more than 1,000 Raspberry Shakes around the world available to anyone who knows what to do with it. The thoughtful choice in data format ensures that Raspberry Shake data can be processed in the same way as that from academia and industry, opening up a world of options for viewing and analyzing. Almost anything you can think of to do with seismic data, says Nesbitt, you can do with free software. For example, Nesbitt says, “the USGS has a great piece of free software called Swarm.” Swarm users can see waveforms, create spectrograms, and even triangulate earthquake locations using multiple seismic stations, he says. Another piece of free software, jAmaSeis, connects students in primary and secondary schools to seismic stations all over the world, including the more than 1,100 Raspberry Shakes that stream in real time. This software “lets students evaluate the data to answer fundamental questions about earthquakes and Earth’s structure,” says Wendy Bohon, an education specialist at the Incorporated Research Institutions for Seismology. Getting seismology in the classroom is a particularly important goal for Raspberry Shake, says Christensen. “I’ve had the joy of going into the classroom and seeing kids using Raspberry Shake… and it is an incredibly gratifying experience,” he says.
— Thomas Lecocq (@seismotom) March 20, 2020
While Swarm and jAmaSeis have some processing capabilities, Nesbitt says they’re built around visualization. For software focussed on processing, many seismologists—professionals and hobbyists alike—turn to ObsPy, a seismology-specific Python toolbox. ObsPy allows users to pull data from Raspberry Shake’s data center using standard tools with no special installation and filter out unwanted waveforms. Such waveforms could include trains, explosions, or even earthquakes, depending upon the question at hand. For many hobbyists, using ObsPy can seem daunting at first, especially without knowledge of Python. Enter Twitter. “Shakers form a vibrant, active group on Twitter,” says Christensen, with many scientists helping hobbyists examine their data with ObsPy. Nowhere has this free flow of information and expertise in seismology been more pronounced than with the anthropogenic noise study, where Lecocq’s initial tweets on Brussels’ seismic lull kicked off a massive collaborative effort. “I thought it was neat to see it start on Twitter with people noticing this phenomenon, and then releasing code,” says Wolin. The Hollisters plan to explore their Raspberry Shake data in more detail than straightforward visualizations with Swarm. “Like most things, the more you learn, you realize there’s more to it,” says Laura, “and you want to get deeper into it.” Ryan Hollister says he wants to learn ObsPy to eliminate the cigar-shaped train signals. As active “geotweeps” on Twitter, the Hollisters will be able to turn to their fellow seismology enthusiasts for help as they learn. “Seismologists with a range of experience” respond to questions on Twitter, says Christensen. “When you look at all the stories about cultural noise, and how… they’re seeing signal where they saw noise before, that was born from observations made both by professional scientists and citizen scientists.” He pauses before saying, “They’re exchanging ideas back and forth, and I don’t think that existed before.”
“Screenshot of ShakeNet, showing global distribution of Raspberry Shakes.”
Lessons from COVID-19 Lockdowns with Raspberry Shakes
by Alan Kafka / January 18, 2021
“The COVID-19 saga began about a year ago and has upended “normal life” for virtually everyone on planet Earth. While a challenging experience for me personally, the pandemic has also been a time of unexpected new directions in my research and teaching. Raspberry Shake seismographs played a major role in that story. Pandemic restrictions motivated me, and many other scientists and academics, to experiment with new approaches to research and teaching. In my case, my research and teaching was notably affected by my involvement in a study of seismic quieting associated with lower levels of human activity brought about by COVID-19 lockdowns (Figure 1). My participation in that study, which relied heavily on Raspberry Shake data, launched me into an adventure that resulted in a paper (published with 76 co-authors from around the world) about this seismic quieting (Lecocq, et al., 2020). My involvement in that study was also significant in my approach to teaching during COVID-19, making all of this much more of a teaching/research synergism than I could have imagined just a year ago.
Figure 1: “Thomas Lecocq and 75 seismologist colleagues from around the world, analyzed hundreds of global stations in their study of COVID-19 seismic noise reduction. About ¼ of those were Raspberry Shake sites. They made use of citizen seismographs in noisy locations to complement other research seismographs in a study of changes in human activity around the world due to COVID-19 lockdowns. When the lockdowns were imposed there was a drop in human activity such as walking, driving, and use of public transportation, resulting in a decrease in ways that humans create seismic vibrations of the Earth. Lecocq et al. (2020) were thus able—with the help of Raspberry Shakes—to quantify the decrease in global human activity due to the pandemic lockdowns.”
In two of my courses—Geoscience and Public Policy, and Environmental Systems: The Human Footprint—we cover the intersection of Earth systems and society. Students taking those courses in the spring of 2020 had a very immediate, personal experience of that intersection. We were faced with the very stressful situation of being told we must immediately leave the campus for the rest of the semester and abruptly switch to online learning. But through this unexpected event, we also experienced a “teachable moment” regarding how humans interact with global Earth processes in ways that can have direct effects on our lives. Although very stressful for all involved, the situation motivated the addition of a new topic for both courses: the intersection of global Earth systems, human population dynamics, and the spread of COVID-19.
Figure 2: “New England earthquakes that were regionally-recorded at Raspberry Shake citizen seismograph sites in the Boston area, and the magnitude 6.4 earthquake in Puerto Rico (also recorded by a Shake in New England).”
While all of that was happening in my teaching, a parallel story was unfolding in my work at Weston Observatory. The observatory monitors earthquakes around the world, and that includes a “seismographs for citizens of planet Earth” project in which we operate low-cost seismographs (now primarily Raspberry Shakes) in schools and other public and private places (Figures 2 and 3). Our earthquake monitoring, our citizen seismology initiative, and my experience of the abrupt transition to online teaching all converged in my involvement in the global quieting study.
Figure 3: “Four seismograms recorded by Raspberry Shakes at citizen seismograph sites in the Boston area from a magnitude 6.9 earthquake in Indonesia. These recordings are of a seismic wave called “PKIKP”, which penetrates deep within the Earth’s outer and inner core and arrives, well-recorded, at the Raspberry Shake sites.”
So, what is this “seismic hush” all about? While adjusting to life in the new pandemic lockdowns, and working mostly online, many seismologists around the world observed a global quieting of seismic noise corresponding in time to the pandemic lockdowns. I observed it in New England, and specifically at two of the Shakes I operate on the Boston College (BC) campus (RA2DE, in the student athletics center, and R57EC, in the building where my courses are taught). Thomas Lecocq (of the Royal Observatory of Belgium) began reporting on the seismic hush he was seeing in Belgium and inspiring other seismologists to get involved with studying that phenomenon at other locations around the world using his open source software. He posted his seismic noise analysis code on the internet, which enabled me to replicate the same processing algorithm that he (and by then a growing number of other seismology colleagues) were using. In both courses it was time for my usual topic of earthquakes, the environment, and the challenge of living on an active planet. This is when I typically discuss seismology, seismographs, citizen seismology, and Weston Observatory’s role in monitoring how the Earth quakes. This year, my students were able to directly experience scientists recording and analyzing the global seismic hush on a seismograph in the same building where their courses are taught! My students could thus see the science unfolding right in their classroom at the same time they were seeing it unfold in the media. And because of the Shake community’s well-established culture of social networking and citizen science technology, it didn’t matter that much that the students were no longer present in the classroom. I could include the students in my emails describing the phenomenon, and they could see my Twitter and Weston Observatory announcements in which I was describing our latest observations on our Shakes at BC to the public and the research community. Teaching these courses became additional motivation for my participation in this research project, and the project was developing in such a way that I could bring up-to-date research into the course experience.
We usually think of seismographs as recording earthquakes, which of course they do, but they also record lots of other things that “shake”, such as athletic events (Figure 4), activities of people near the seismograph (Figure 5), and vehicle traffic near the site. In the case of typical research seismographs, we try to install them (to whatever extent possible) in seismically quiet places so that earthquake signals won’t be obscured by signals from other sources of seismic waves. Citizen seismographs, by contrast, can be quite noisy because they are often purposely installed near people and other human cultural noise sources. We want our citizen seismographs to be near where the people are. That can be a problem for seismic monitoring of earthquakes, but it’s not always bad for other aspects of seismology.
Figure 5: “Four days of recording at Amesbury (MA) Middle School. Top row is the two of the days before the COVID-19 lockdown at the school, and bottom row is two of the days after the lockdown. The effect of students in the classroom during the two days before lockdown, and the quieting afterward, is clearly observed.”
At schools we usually put the seismographs in classrooms or other locations where there are a lot of students, so the school seismographs are usually noisy. But these noisy sites turned out to be just the right settings for seeing the effects of the pandemic lockdowns. Shortly before the lockdowns, I had installed a Shake at Amesbury MA Middle School (in a classroom with many students). I recognized the downside of having the seismograph right in the classroom, but it was also valuable for the students to be directly involved with the seismograph and what it’s recording. When Amesbury Middle School was locked down, the seismic noise quieting effect was very clearly observed there (Figures 5 and 6).
Figure 6: “Examples of seismic noise analysis using the open source computer code provided by Thomas Lecocq: Amesbury Middle School and Devlin Hall & Conte Forum at BC are Shake data. The seismograph at Westport Astronomical Society (located in a Connecticut suburb of the New York City metropolitan area) is a much more expensive “research-grade” seismograph (part of Weston Observatory’s New England Seismic Network). The seismic quieting after lockdown times is clearly observed.”
When the COVID-19 lockdowns were imposed, leading to the drop in human activity (such as walking, driving, and use of public transportation), that meant there was a drop in the ways that humans create seismic vibrations of the Earth. The global team of 76 seismologists were thus able, with the help of Raspberry Shake seismographs, to quantify the decrease in global human activity due to the pandemic. A global summary of the observations of the seismic quieting, and its relationship to the lower levels of human activity, is presented in Lecocq et al., Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures (2000). The study was based on analysis of hundreds of global seismograph stations, and about ¼ of those seismographs were Raspberry Shakes. So, in addition to the basic research dimension of this study, it was also a good example of how low-cost citizen seismographs can contribute to a real science research project.
And the value of citizen seismology was highlighted by the fact that so many of the seismographs used in the study were Shakes located at schools and other citizen seismology sites. In addition to our study of seismic noise on the BC campus, my colleague Jay Pulli and I are studying seismic noise recorded by a Shake (RAC22) at a suburban site near Washington, DC (Pulli and Kafka, 2020). Figure 7 shows seismic noise at the BC and DC sites, along with variation of human activity before and after the imposed lockdowns (depicted by human activity data from apple.com/covid19/mobility). The next phase of our research involves untangling specific local effects of COVID lockdowns from the mixture of regional and global patterns. Broad trends of the noise data generally correlate with the mobility data, which reflect activity over the larger Boston and DC regions, but that broad pattern is undoubtedly mixed with noise from nearby sources. We are exploring the extent to which the fluctuations around those broad trends seen in Figure 7 can be explained by differences in nearby sources superposed on the regional and global effects. For example, the Conte Forum BC athletics center is nearer to commuter and campus vehicle traffic than Devlin Hall.
Figure 7: “Latest results showing details of the fluctuation of seismic noise along with mobility data for: Conte Forum and Devlin Hall at BC, and for the suburban Washington, DC site (Oakton, VA). The seismic quieting after lockdown times, and evidence of a return to higher levels of human activity in more recent months, are clearly observed.”
Pulli and Kafka (2020) also applied a model of vehicle traffic noise from nearby roads to explore the pattern observed at the DC site. In that study, traffic noise was modeled to estimate the expected noise level from traffic on roads near the site. We also plan to apply that model to the BC data, modeling the effects of traffic around the BC campus and other possible noise sources. This new area of research that I have been fortunate to be involved in is part of what we are now referring to as “Social Seismology”, which provides citizen scientists with a new way of seeing how much humans affect planet Earth. With a Raspberry Shake seismograph, you can see your own personal effects on local, regional, and global seismic monitoring. Social Seismology also highlights new ways for scientists to use social networking and internet technology to connect with each other and to connect with a more public audience, making science more approachable for a wider audience. Nobody expected the pandemic to be such a major part of all aspects of our lives, including a wide range of science research, and specifically seismology. Through a series of events that nobody involved could have imagined, low-cost Raspberry Shake citizen seismographs have been shown to be useful as an integral part of basic research. And that’s how Raspberry Shakes linked seismic moments with teachable moments during COVID-19 lockdowns.”
Here's the latest #SocialDistancing seismic background noise levels for Los Angeles!
Human-made sources of ground motion (like cars, industry, & even walking) decrease as folks stay home, so isolation efforts can be observed with seismometers. Stay safe & keep that ground quiet! pic.twitter.com/suzKZodJK9
— Celeste Labedz (@celestelabedz) April 6, 2020
Kafka, A.L., and J.J. Pulli (2020), The COVID-19 Seismic Noise Quiet as Seen by Two Raspberry Shake Seismographs Located at Boston College, Fall 2020 Meeting of American Geophysical Union, December 1-17, 2020.
Kafka, A.L. (2021). “Blog book” for Geoscience and Public Policy course, sites.google.com/bc.edu/geoscience-public-policy-v3/home
Lecocq, T., et al. (2020, including 75 coauthors, see Figure 1). Global Quieting of High-Frequency Seismic Noise Due to COVID-19 Pandemic Lockdown Measures, Science, 10.1126/science.abd2438.
New York Times article (2020). Coronavirus Turns Urban Life’s Roar to Whisper on World’s Seismographs, nytimes.com/2020/04/08/science/seismographs-lockdown-coronavirus.html
Pulli, J.J., and A.L. Kafka (2020), Decrease in High-Frequency Background Seismic Noise after the COVID-19 Lockdown at a Suburban Site Outside Washington DC, Fall 2020 Meeting of American Geophysical Union, December 1-17, 2020.
RaspberryShake.org (2020). Citizen Science at Heart of New Study Showing COVID-19 Seismic Noise Reduction, raspberryshake.org/citizen-science-at-heart-of-new-study- showing-covid-19-seismic-noise-reduction/
Tripathy-Lang, A. (2020), As the World Quieted Down in 2020, Raspberry Shakes Listened, arstechnica.com/science/2020/12/as-the-world-quieted-down-in-2020-raspberry-shakes-listened/
Washington Post article (2020). Earthquake sensors record unprecedented drop in human activity due to pandemic, washingtonpost.com/science/2020/07/23/human-seismic-noise-coronavirus
DID YOU FEEL THAT?