A new study by a pair of French researchers says patterns in GPS data that measure fault slips found they often precede large earthquakes by as much as two hours, offering hope for predicting such catastrophic events before they occur.
Previous efforts dating back to the 1970s have failed to find a reliable method for predicting large earthquakes, but the researchers behind these findings say that their work could finally lead to such a method, potentially saving millions of lives.
A Reliable Method for predicting earthquakes Has Remained Elusive for Decades.
As far back as the 1970s, seismologists and geologists started to surmise that finding a way to predict earthquakes well before they occur must be possible. Some studies seemed promising at first, and one honest-to-goodness official prediction actually occurred in Haicheng, China, in 1975.
A further review of that event seemed to indicate that there was a lot of luck involved, and by the 1980s, most serious efforts to predict earthquakes had been abandoned or shelved until technological improvements could potentially make them more viable.
Now, a team of French researchers says they have found a relatively reliable pattern using the relatively modern tool of Global Positioning Systems (GPS) that could potentially offer an earthquake warning nearly two hours before the shaking occurs.
Fault Slips Seem to Indicate Predicting Seismic Events with GPS is Possible
Published in the journal Science, the research by Quentin Bletery and Jean-Mathieu Nocquet from the Universite Côte d’Azur, IRD, CNRS, shows that a series of slips along the fault that is about to cause a quake can be spotted by GPS tracking.
“In the past decade, the idea has grown that large earthquakes initiate with a potentially observable slow aseismic phase of slip on the fault, associated with increased microseismicity,” they write. “On the basis of either geodetic or seismic data, these studies suggest that earthquake precursors exist and that, therefore, earthquakes could be anticipated minutes, days, weeks, months, or even years before they occur.”
Unfortunately, the researchers note, much of this data is gleaned from only a few earthquakes, and the methods proposed or studied seem to generate a lot of false positives. However, they say that one method they are studying may actually hold significant promise.
“One exception is a global analysis of the seismicity preceding large earthquakes, which does find an exponential increase in the number of earthquakes ranging from years up to hours preceding large events,” they explain.
In total, the team looked at data from 90 earthquakes larger than magnitude 7 by using data from 900 GPS stations from around the globe. That work involved a lot of number crunching to remove all other possibilities for the pattern they thought they were seeing. But in the end, they determined that given the right GPS data and timely analysis, large earthquakes could often be reliably predicted in the hours before they occur.
“Our analysis indicates that, on average, earthquakes start with a ≈2-hour-long exponential-like acceleration of slow slip,” they explain.
The researchers also point out that their research may have only revealed the final stages before an earthquake, and analysis of foreshock activity “also suggests exponential acceleration of fault slip but over a much wider range of timescales.” Those patterns, they note, should be studied further.
Not All Researchers are Convinced Slip Events Mean an Earthquake is Coming
A companion piece written by Roland Bürgmann, a professor of Earth and Planetary Sciences at the University of California, Berkeley, seems to offer both support and skepticism regarding the potential for earthquake prediction using slow slip fault line events.
“There is a long history of retrospective studies, carried out after a large earthquake has already happened, that suggests a wide variety of possible precursors that could potentially have been used to predict the earthquake,” Bürgmann writes.
However, he also writes that such precursor signals are not always reliable, as “natural foreshocks cannot be distinguished from similar clusters of background seismicity, and observed slow preslip events have not appeared different from geodetically measured slow slip transients that occurred without being followed by a large earthquake.”
The UC Berkeley professor also questions if the data found by the French researchers is everything they claim it could be.
“Although the results of Bletery and Nocquet suggest that there may indeed be an hours-long precursory phase, it is not clear whether such slow-slip accelerations are distinctly associated with large earthquakes or whether they could ever be measured for individual events with the accuracy needed to provide a useful warning.”
Ultimately, both the original researchers and Bürgmann agree that much more data collection and analysis is necessary, but if their analysis holds true, then the ability to predict earthquakes as much as two hours before they occur could end up saving millions of lives.
“If it can be confirmed that earthquake nucleation often involves an hours-long precursory phase, and the means can be developed to reliably measure it, a precursor warning could be issued, letting people know that it is time to let go of sharp utensils and get ready to “Drop, Cover, and Hold On,” before the Big One strikes,” Bürgmann concludes.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on Twitter, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.