Cracking the Earthquake Code
Do earthquakes provide magnetic warning signs? Roberta Kwok puts her ear to the ground.
Illustrated by Sarah Adler and Lauren Benson.
Illustration: Sarah Adler
Tom Bleier is praying for an earthquake. An engineer who designed and built his own house, Bleier lives on a densely wooded ridge in Portola Valley, California, less than half a kilometer from the San Andreas fault. In a nearby field, he’s planted an instrument to track magnetic signals from the Earth. It’s a gangly contraption resembling a hotel mini-fridge on stilts.
“We’ve been desperate for another earthquake,” he says.
Bleier doesn’t have a death wish. His company,
QuakeFinder, monitors a far-flung network of these sensors along California’s fault lines, from Eureka to the Mojave Desert. They’re banking on an old and controversial theory that blips in a region’s magnetic field could herald the rumblings of the most destructive earthquakes. With enough luck, Bleier believes, QuakeFinder will predict them.
The mere mention of earthquake forecasting—a field populated by reports of mysterious lights, unexplained temperature shifts, and highly attuned cats—is enough to make some geophysicists roll their eyes. But magnetic alarms aren’t just quackery, insists a small cohort of researchers. Bleier claims one of his sensors picked up magnetic pulses before a magnitude 5.4 quake that shook the Bay Area in October 2007. A NASA physicist has found that rocks generate electricity under stress, offering a possible explanation for magnetic jitters at the surface. And Stanford University engineer
Antony Fraser-Smith, whose observation of a signal before the 1989
Loma Prieta quake remains the strongest evidence to date, is so frustrated by the scientific community’s lukewarm response that he’s lobbying members of Congress to set up magnetic sensors at earthquake hotspots around the world.
“We have 34 million people in California all sitting around and paying taxes and expecting the federal government to do something about earthquakes, and yet no one is trying to verify those measurements,” Fraser-Smith says. “It really irritates me.”
Magnetic signals could do for earthquakes what weather satellites did for hurricanes, giving people enough time to locate their families, move to safer areas, and turn off fire-igniting gas lines, Bleier says. But critics of earthquake prediction, burned by exaggerated claims before, remain deeply skeptical. A region’s magnetic field is a morass of meaningless noise, they say, warped by everything from solar activity to electric trains to cell phones. From their perspective, deciphering a real earthquake signal amidst the junk is akin to picking out the hum of a single car zipping past on a crowded freeway. And researchers have failed to link these signals consistently to all earthquakes, making the claim of predictive ability “at best, a vast overstatement,” says
Richard Allen, a seismologist at UC Berkeley.
So far, the nation’s primary earthquake-monitoring agency, the U.S. Geological Survey (USGS), has declined to fund Bleier’s work. “We’re hanging on by a thread,” he says. QuakeFinder subsists on money from its parent company, the aerospace engineering firm
Stellar Solutions, and a small NASA grant. But unless it detects a signal from the next big quake, the company’s network of sensors—the largest in the world, its website claims—will probably disappear.
Messages from the underground
Earthquake prediction has fallen on its face before. In the 1970s, scientists declared they could detect upcoming earthquakes by monitoring bulges in the ground, a strategy that failed upon further testing. A Greek group created a furor in the 1980s with claims that electricity sensors could successfully predict earthquakes, but critics called their data contaminated and their predictions too vague. Meanwhile, reports of magnetic signals trickled in, including spikes recorded before earthquakes in Alaska, Armenia, and Guam.
The most startling example arrived in 1989, when the magnitude 6.9 Loma Prieta earthquake struck the San Francisco Bay Area. At the time, Fraser-Smith was monitoring magnetic fluctuations in the Santa Cruz Mountains for unrelated research on Navy submarine communication. His sensor was only seven kilometers from the epicenter. When he checked the sensor’s records after the quake, he found the first magnetic wobbles a month in advance, followed by a lower-frequency roar. In the hours before the quake, the signals were so big that the computer spat out calibration error messages—the first such warning in the instrument’s two years of monitoring.
Fraser-Smith’s report at that fall’s American Geophysical Union meeting immediately attracted attention. The USGS asked him to monitor
Parkfield, a quake-prone area in Central California, but pulled his research funding after several years went by without a rumble. (During that time, Fraser-Smith failed to pick up a signal from the deadly
Northridge earthquake, a result he attributes to his sensor being too far away.) Opposing teams wrangled over the meaning of Fraser-Smith’s Loma Prieta data at a 2007 geophysics meeting in San Francisco, with USGS scientists on both sides. One group concluded the spikes were just data corruption.
“It was a real stab in the back,” says Fraser-Smith.
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Photo: Roberta Kwok |
Stanford engineer Antony Fraser-Smith displays his magnetic recordings from October 1989, when a large earthquake struck near Santa Cruz, California. |
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Now a retired professor with white hair brushed neatly back from his forehead, Fraser-Smith still keeps wrinkled graphs of his Loma Prieta measurements posted on his wall at Stanford. In a clipped New Zealand accent, he dismisses the idea that scientists can’t tell new signals apart from the familiar patterns of background noise.
“I am an expert, and we have no trouble distinguishing these signals,” says Fraser-Smith. “I have tremendous confidence that electric and magnetic field measurements will tell us a whole lot. And yet they’re just not being used. It’s really, really sad.”
Fraser-Smith plans to write members of Congress proposing a network of sensors around the Pacific Rim—the so-called
“Ring of Fire” where earthquakes frequently strike. Three years of monitoring, he estimates, could support or undermine a connection between magnetic signals and earthquakes. The equipment would cost $3 million, an “absolutely piddling” sum compared to other large research projects, he says. To support his argument, he points to reports of other signals. And to a Biblical proverb: “Where there is no vision, the people perish.”
Bogus signals?
One of Fraser-Smith’s apostles is Tom Bleier. A satellite engineer who studied earthquake signals as a hobby for several years, he still remembers hearing about the Loma Prieta report.
“I was applauding from the back of the room,” says Bleier, who is nearing retirement but speaks with the enthusiasm of a boy showing off his first Lego creation.
Bleier decided to build his own network. With science outreach funding from his employer, Stellar Solutions, he began constructing instruments with local high school students. In 2000, he started QuakeFinder and convinced farmers to let him set up sensors in their fields. Now in its eighth year, QuakeFinder has 70 sensors ranging from the Oregon border to the Southern California desert, all transmitting data to an office in Palo Alto.
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Photo: Roberta Kwok |
Tom Bleier, founder of the QuakeFinder network, stands with a magnetic sensor in Portola Valley, California, south of San Francisco. |
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Some transmissions, Bleier believes, contain strange signals from the October 2007 Alum Rock earthquake near San Jose. “What the heck are those spikes?” he asks, pointing to a graph resembling an EKG plot at QuakeFinder’s offices. The signals started in September and increased as the earthquake approached, bombarding the nearest sensor with at least 1,000 pulses a day and, as in the case of Loma Prieta, continuing for several days after the initial shock. Similar spikes show up occasionally on other stations, but Bleier suspects the tight Alum Rock cluster may have been a warning sign.
QuakeFinder’s engineers are now on a “CSI” mission, as Bleier calls it, to make sure the signals didn’t come from somewhere else. They’ve checked electrical equipment on the property, the effect of passing cars, and the timing of laser blasts from a nearby laboratory. The team still needs to analyze past transmissions to see whether the Alum Rock pattern is truly unusual, Bleier says. Even if it is, he isn’t optimistic about how others will react. “People will throw rocks at it,” he predicts.
Scientists already are raising questions. Malcolm Johnston, a member of the USGS team that critiqued Fraser-Smith’s work, says QuakeFinder’s results suffer from the same pitfalls as other claims of magnetic precursors: They were recorded in an environment clogged with noise, and because QuakeFinder’s sensors are widely spaced, they only appeared on one station.
“Any data on a single instrument is suspect, and anybody in the game will tell you that,” he says.
Earthquakes do generate magnetic signals, Johnston says, but these generally occur during or after the quake. After searching for 30 years without success, he believes precursory signals are too small to be picked up. Johnston points to the magnitude 6.0 Parkfield earthquake, which finally arrived in 2004 and was surrounded by a phalanx of high-sensitivity instruments. The quake remained magnetically mum.
These results make it hard to justify the global network Fraser-Smith envisions, Johnston says, though Fraser-Smith believes the Parkfield quake was simply too small to send a signal. Johnston is dubious about the historic signals Fraser-Smith claims as evidence; the Alaska measurement, for instance, was taken in a motel parking lot where engines and moving cars might have caused magnetic disruptions. As for older reports, Johnston says the signals go to nearly zero once scientists use modern techniques to remove sources of noise produced by Earth's atmosphere.
“Almost certainly most of this is bogus,” he says.
Snap, crackle, rock
NASA physicist
Friedemann Freund is used to deflecting skepticism. Described by a fellow scientist as a “thoroughly charming gentleman,” Freund speaks in the same gentle tone of voice whether he’s explaining the movement of particles, denouncing seismologists for their close-mindedness, or recalling the time he was hit by a bullet during a rock impact experiment. (“It hurt a little bit,” he says.) His research, he says, could hold the key to explaining magnetic signals.
“I came up with this relatively childish idea,” says Freund in his Mountain View office. He’s nursing a broken arm from a hiking accident, but he holds up a small piece of black basalt with his good hand. “In the moment we start squeezing this,” he says, pressing the rock between his fingers, “we start to see that this rock generates electricity.”
To test his theory, Freund salvages meter-long slabs of leftover granite from cemetery monuments and kitchen-counter stores. He hauls them into his laboratory at NASA's Ames Research Center, squeezing them between metal pistons to produce electrical pulses that zing at 200 meters per second. Fraser-Smith and other scientists question whether these experiments will translate to the Earth’s crust, since water could short-circuit the current. But Freund says it’s possible under the right conditions. Imagine giant masses of rock underground, add the crushing stress of an earthquake, and you could get “big, big-time electric currents,” he says.
Freund believes a little-known chemical exchange in the rock jolts the current into action. Some of the mineral’s oxygen atoms are one electron short, leaving electron “holes.” Stress throws the oxygen atoms into chaos, making their electrons—and the holes—jump from one atom to the next, Freund says. He compares the situation to a movie theater with only one empty seat: If each person shifted from one seat to the next, the empty seat would appear to move, just as electron holes move through the rock. The moving holes could generate strong fluctuating electric currents in the Earth, according to Freund, and cause magnetic changes at the surface.
The theory could also explain a slew of other pre-earthquake phenomena besides magnetic signals, Freund says. For instance, satellites have reported areas shining in the infrared before earthquakes. These infrared signals could be released by oxygen atoms that pair up at the surface of the rock, he says, adding that he has produced such emissions in the laboratory. Other people have photographed strange lights before earthquakes; Freund attributes these to electron holes that create a positive charge in the air, leading to a bright corona discharge. According to Freund, even odd animal behavior can be explained by experiments from the 1960s showing that animals shy away from positively charged air.
“The more I dug into this, the more I realized that all the phenomena fall into place if we understand the physics of these electron charge carriers,” Freund says. “Suddenly things become very easy.”
Scientific sex appeal
Earthquake prediction researchers do have some allies.
Alan Linde, a geophysicist at the Carnegie Institution in Washington, D.C., believes Fraser-Smith’s Loma Prieta measurements are sound and says he was “totally unpersuaded” by the data-corruption criticism. But the question of whether the quake caused the signal is much more difficult, he says. Coming up with more evidence won’t be easy; to get instruments close enough to the epicenter, he notes, you almost need to predict the earthquake’s location anyway.
“Earthquake prediction is a hell of a sexy objective, and the temptation to get a wonderful answer is high,” Linde says. Although a few bad studies may give the field an air of disrepute, Linde believes the research should go on. He likens earthquake forecasting experiments to playing the lottery: You might end up with nothing, but the payoff could be huge. “That’s how breakthroughs are made, doing experiments that have a small chance of return,” he says.
But if scientists want to use magnetic signals to predict earthquakes, they need to observe them before all earthquakes, not just some, says Richard Allen of UC Berkeley. So far, that hasn’t happened. “They have a whole list of excuses, or reasons, as to why you don’t see them,” he says. “The idea that we would somehow miraculously see these signals before future large earthquakes is not founded in any actual information.”
Instead of trying to predict earthquakes, Allen argues, we should focus on being better-prepared for them. What people really want, he says, is for life to go on as usual after a quake—and the best way to accomplish that is by constructing better buildings. As an “extra blanket” of protection, Allen’s team also is developing a warning system based on an earthquake’s first tremors (see sidebar).
A fair shake?
If QuakeFinder goes under, a more modest operation is ready to step in. A USGS-led group of San Francisco Bay Area scientists has scraped together NASA funding to monitor magnetic activity in the San Francisco Bay Area. The team plans to install closely spaced sensors in two quiet areas to increase the chance that a signal will appear on multiple stations.
“The bottom line is this sort of work has to be done much better if we are going to convince anybody that there’s any reality in these sorts of signals,” says Johnston, who will lead the study with USGS geophysicist Jonathan Glen.
Even if they pick up a signal, it won’t necessarily lead to an earthquake prediction system, Glen says. Rocks could emit wildly different signals depending on the area’s geological features and fluid content, making confident predictions difficult.
“We are really far, far away,” says Glen, who plans to exchange data with QuakeFinder. “There is definitely the potential. But to say we are anywhere near there is disingenuous. I think it’s misleading.” While QuakeFinder’s widespread network has a better chance of catching a signal, Glen believes his team’s strategy will be more effective at determining whether a signal is truly an earthquake precursor.
Fraser-Smith is prepared to accept the possibility that earthquakes don’t transmit magnetic warnings, saying that it would take at least 10 or 15 other examples to convince him. “I would just like to know the truth before I die,” he says.
It could be a while before scientists settle the question. “The Earth’s utterings are faint and often confusing and few claim to know how to read them,” Freund wrote in a 1999 article. Decades of research have shown the difficulty of interpreting potential earthquake signals. Unless scientists can learn to translate its messages, the Earth may remain a closed book.
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Sidebar: Take Cover!
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Illustration: Laura Day Benson |
If long-term earthquake forecasting doesn’t pan out, how about a few moments of warning? Scientists at UC Berkeley have developed a system that could size up an earthquake and sound an alarm several seconds before the ground turns to Jell-O.
Earthquake early-warning systems already exist in countries such as Japan, Mexico, and Turkey. Mexico’s system, for instance, monitors the stirrings of an offshore fault in the Pacific Ocean and outruns the earthquake’s most destructive waves to Mexico City. But California presents a special challenge because its citizens live precariously close to major fault lines, leaving little time to broadcast an impending quake.
“We’re trying to build a system that absolutely minimizes delays because if possible, we would like to issue warnings to people living right in the epicenter region,” says seismologist and project director Richard Allen.
To make the speediest decision possible, Berkeley’s
ElarmS system squeezes information from the first few seconds of underground pulses to calculate the magnitude and location of the quake. If the waves are small and close together, the threat level goes down; if they’re large and far apart, a giant temblor is likely on the way. ElarmS then draws on data from past earthquakes to predict the intensity and distribution of ground shaking, creating a nearly instant map that could lead to automated warnings.
The team put its system through a hands-off test run in 2006 to see how it performed without human guidance. Over the course of eight months, ElarmS crunched the numbers on 75 small earthquakes in northern California. Simulated warning times to major cities clocked in around 40 to 60 seconds. In October 2007, the system accurately predicted the magnitude and ground shaking of the magnitude 5.4 Alum Rock earthquake before anyone felt the shaking in San Francisco, Allen says.
ElarmS isn’t yet a full-blown warning system. “The other half of the problem is how we get that information out to people and how people should use that information,” Allen says. He speculates that alarms could be issued through the Internet, cellphone towers, or radio. Transportation systems and dangerous industries could shut down automatically, and people could move to safety. But first, his team must make sure ElarmS is accurate and rock-solid.
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Biographies
 Roberta Kwok
B.Sc. (biology) Stanford University
M.F.A. (creative writing) Indiana University at Bloomington
Internship: Idaho National Laboratory news office
It started with sunflower puberty. I was an English student moored in the Midwest, writing short stories and celebrating my recent escape from the cubicles of Silicon Valley. Chekhov had replaced Mendel; my training in biology and computer science had begun to seep away.
Then one cold March day, I spent 24 hours tailing a young evolutionary biologist who wanted to find out how sunflowers decide to flower, or enter “puberty.” I followed him into greenhouses, recorded his words (including the expletives), wrote his story—and realized that language could bring the humanity back into science. I could fight misunderstanding with metaphor, boredom with wordplay. Most importantly, I could make scientists as real as any figure in a Chekhov story: human, vulnerable, full of error.
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 Sarah Adler
B.A. (fine art) University of California, Santa Cruz
Growing up in northern California, I fell in love with the natural world at an early age. I always wanted to be outside sneaking off in my imagination surrounded by plants and animals. I was fortunate to attend a Waldorf school for several years, which triggered my passion for painting and drawing early on. Over the last ten years, my art has consistently portrayed the beauty and complexity of nature. I have always hoped to inspire others with my art to realize the preciousness of the world around us and the importance of its preservation. Once I heard about science illustration, I knew it was the perfect combination of my interests in our environment as well as my passion for its beauty.
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 Lauren Day Benson
B.A. (art and feminist studies) University of California, Santa Cruz
I have aspired to be a scientific illustrator since high school when my teacher, Leo Kenney, introduced scientific illustration as the perfect synthesis of art and nature appreciation. My goal as a scientific illustrator is to use artistic representation to communicate scientific concepts and subjects to the public. My summer internship is at the Sierra Nevada Research Institute (Scientific Visualization Fellowship).
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