Scientists across the globe have searched for a way to predict when an earthquake would hit, but struggled to find an accurate, testable method. Now, a research team believes they may have found "significant" new evidence in detecting these seismic events.
The team of researchers, comprised of two scientists from Japan’s Tohoku University and two scientists from the University of California, found a previously unrecognized pattern that occurs just before large earthquakes, reports Phys.org.
Large earthquakes seem to be prefaced by silent and subtle deformation called “slow-slip events,” according to the study. These occur almost periodically in the megathrust zone in Japan, but are still unpredictable on a large scale. They take place every 1 to 6 years and have often correlated with large earthquakes.
Researchers first observed the occurrence was during the magnitude-9.0 quake that rattled northeastern Japan in 2011, Voice of America (VOA) reports. Uchida and her colleagues reviewed data that showed subtle slips began to accelerate days before the massive quake, which spawned a deadly tsunami.
“Although it will be a long way to make the earthquake predictions that are useful for society, I believe this is a significant step toward that,” lead author Naomi Uchida told VOA.
Uchida and her colleagues analyzed seismic data dating back to 1984 for two of Japan’s largest islands, Phys.org also reports. From this data they were able to identify 1,500 examples where there seemed to be a pattern of repetition, which allowed them to gauge the speed of the tectonic plates underground.
From these statistics, they matched slippages with non-repeating measurable quakes that had a magnitude of 5 or higher. Their results indicated that there appears to be a speedup of slippage just before major earthquakes. GPS data was also used to measure tectonic shifting and reportedly matched the rates they previously calculated.
“The results suggest the possibility of an earthquake is larger when slow slips are occurring,” said Uchida. “By taking account of such relationships, the probability forecast of earthquakes can be improved.”
Some researchers still remain doubtful of the reliability of using slow slips to predict earthquakes.
“I think the best we could hope for from slow-slip events would be the same sort of modest probability gain,” said University of California-Los Angeles Earth and space sciences professor emeritus David Jackson.
According to University of California-Berkeley statistics professor Philip Stark, until testable predictions surface, “they have an interesting anecdote, not a fundamental discovery.”
The team is aware that there is much more research left to be done before this discovery can becomes an official early warning system.