Just as with any academic community, the world of geophysics is much divided. While a good number of scientists see as their central mission the need to be able to predict earthquakes, many utterly abhor the notion. Charles Richter (he of the Scale) was vehement: “I have a horror of predictions and predictors,” he wrote in 1977. “Journalists and the general public rush to any suggestion of earthquake prediction like hogs toward a full trough.”
This week I have found myself in the midst of a schism, one that has become apparent in the aftermath of Japan’s Great Tohoku Earthquake of March 11. That catastrophe has reignited a vigorous argument over whether the various grave geological events that have lately occurred around the Pacific’s so-called Ring of Fire—severe earthquakes in New Zealand, Chile, and now Japan—have left the thus-far seismically untouched Pacific coasts of the United States and Canada peculiarly vulnerable. It is a dispute over the notion of "earthquake prediction," more technical than philosophical, and in essence it revolves around two related questions: Do earthquakes occur in clusters, both in time and place? And if they do, might one quake trigger another?
Large numbers of concerned lay observers—who are generally discounted, reasonably enough, by the geophysical community—believe on the basis of recent experience that some kind of linkage between the recent quakes is blindingly obvious. As all newspaper readers must agree, there seem to have been an awful lot of very big earthquakes lately—Kashmir, Sichuan, Haiti, Sumatra, Valparaiso, Christchurch, Sendai—all since 2005.
But such anecdotally based conclusions do not make sense to many geophysicists, who have clogged up the blogosphere in recent days to say so. Typical of these is Andy Frassetto, a post-doctoral researcher at the University of Copenhagen: The idea “of seismic clustering should not be mistaken for a valid scientific concept…it gains legitimacy through repetition in the media,” he writes. “I cannot think of one seismologist who would consent that large earthquakes can be triggered by other large earthquakes occurring thousands of kilometers away. In such a case, would we be safe anywhere?!”
His view is echoed by Christie Rowe, also a post-doctoral researcher at the University of California, Santa Cruz, who writes, “There is no evidence to support the idea that triggering of earthquakes should be related to shared plates—as the entire planet is affected by the seismic waves from large earthquakes, the next big one might as well be in the Himalayan Frontal Thrust or the Northern Anatolian Fault.” In other words, an earthquake in Japan might, if triggering were ever to be proven, cause something in Kashmir or Turkey, and it is both irresponsible and provocative to suggest that it would more probably trigger an event on the same tectonic plate family, as in California or western Canada.
Chile-Christchurch-Sendai—to a lay person, the linkages are as plain as the nose on your face.
But in some quarters, the view is not so doctrinaire. Harold Tobin, professor of Geophysics at the University of Wisconsin, while highly critical of what many of his colleagues deride as "scare-mongering," said that he is not entirely opposed to the clustering idea. “There is an intriguing hypothesis gaining some momentum that earthquakes do occur in clusters, even at long distances,” he wrote. “It is hardly a matter of little doubt. It’s a very new idea, and quite controversial.”
But before mentioning some of those who labor in this very new cluster-trigger field, I have to take courteous issue with Tobin. I wonder if the possibly too-narrow focus of some geophysicists’ perspective keeps some from seeing what is, to others, just plain obvious. For why, indeed, is the notion of clustering so new, so revolutionary?
Geologists have long known, for instance, that the infamous San Francisco earthquake of April 18, 1906, was narrowly preceded by two other devastating events around the Ring of Fire—an earthquake and tsunami off the coast of Ecuador in January 1906, and a powerful earthquake in southern Formosa—Taiwan today—in mid-March. Was that not a cluster? Might Formosa not have played some role in triggering San Francisco?
Much more recently, they must have surely recognized some trans-Himalayan connection between the great Kashmir quake of 2005 and the Sichuan disaster over the hills 30 months later. Were they not linked? Did not Kashmir help release the hairspring that underpinned western China?
Geophysicists do now publicly acknowledge one rather bizarre and provable link. It connects Alaska and Montana, two thousand miles apart—and it was realized after scientists observed that earthquakes on the Denali Fault are swiftly followed by a speeding-up of many of the geysers, of all things, in Yellowstone National Park. Linkage? Triggering?
And now, the Pacific Ring events of Chile-Christchurch-Sendai. To a lay person, the linkages are as plain as the nose on your face.
Yet only a very few scientists agree to say so. Ross Stein, a pre-eminent U.S. government geophysicist at the USGS in Menlo Park, California, is a believer in triggering mechanisms. He is certain, for instance, that the famous 1975 Landers earthquake, near Palm Springs, was linked to and most probably caused some 60,000 shocks in and around Mt. Shasta, 800 miles to the north. Yet he is currently a chastened man. He told The New York Times recently that his community was “humbled” by the lack of real knowledge, despite half a century’s worth of costly (and largely publicly funded) research, about what was truly going on underground. New faults, new structures, kept rupturing, kept causing quakes. “It’s shameful, but we’ve barely scratched the surface.”
Chris Goldfinger, associate professor of marine geology at Oregon State University, is much more unequivocally in the cluster-trigger camp. His particular interest is in the Cascadia Subduction zone, the gigantic undersea fault system that, in his view, poses the gravest of all threats to the Pacific Northwest. “It’s of course connected to the Ring of Fire by other faults,” he is quoted as saying in a new book Cascadia’s Fault, due out this spring by the Canadian author Jerry Thompson.
“We have the Queen Charlotte Fault going off into Canada and the San Andreas Fault going off into California, and all of these faults are physically connected. People used to think that fault lines were isolated from one another, but this doesn’t make sense anymore,” Goldfinger said in a recent interview, after promising that the Pacific Northwest was long overdue for a major quake. “Every piece of the earth is connected, so when one moves it is no longer surprising that the other pieces around it can be affected. When you move one, it affects the others.”
And this idea—that when you move one, it affects the others - is the underlying argument, behind the notion that large earthquakes on one side of a major tectonic plate system may cause, or in some way lead to, events on the plate’s far side. And this is why it is far from inconceivable that the temblors in Chile, New Zealand, and Japan may cause, or lead to, events elsewhere—including in what is unarguably the most vulnerable part of all, the American and Canadian west.
The province of British Columbia, and the states of Washington, Oregon, and California, are due for a big earthquake and a major tsunami. The rupturing of the San Andreas (which last ruptured in 1906) or the Hayward Faults will cause the earthquakes; the much more critical possibility of what is called a full-margin rupture of the Cascadia Subduction zone (which last ruptured in 1700) will cause an immense run of tsunamis. How large these events will be, how deep or shallow—and most importantly, when they will happen—all remain unknown. All that can be said with certainty is that they are more likely to break tomorrow than yesterday.
Are we prepared? Are the buildings in Victoria ready to withstand massive ground-shaking and mighty waves? Are the highway bridges in Portland and Seattle sufficiently strong to cope with the kind of forces unleashed in Japan? Why has it taken 22 years for the Bay Bridge across San Francisco Bay to be retrofitted after a relatively modest quake which caused part of it to collapse in 1989? Are Californians as ready as they might be to deal with the psychological trauma caused by destruction, evacuation, and death on a legendary scale?
All these questions need to be addressed, and addressed more urgently now. If it has taken a brutal trinity of events around the Pacific’s Ring of Fire to bring that sobering reality home, then maybe, at long last, those who live their lives among the stunning beauty of the West Coast may accept that this has become, to use a phrase of the day, "a teachable moment." Though not before time.
