A new study by a Stanford professor has found out a possible method to provide predictions about large earthquakes before they strike.
According to Antony Fraser-Smith, professor emeritus of electrical engineering and of geophysics, Stanford, the method to detect earthquakes has been buried in scientific literature for over 40 years.
Now, with new research, the professor has claimed that he has evidence that big tremors emit a burst of ultra-low-frequency electromagnetic radio waves days or even weeks before they hit.
In 1989, Fraser-Smith and his research team detected one such signal while monitoring ultra-low-frequency radio waves in a remote location in the Santa Cruz Mountains.
The signal that the team received on Oct 17th, 1989, jumped about 20 to 30 times higher than what the instruments would normally ever measure. The researchers were surprised to find that in the evening, an earthquake measuring 7.1 on the Ritcher Scale hit the Monterey Bay and San Francisco Bay areas, killing 63 people and causing severe damage across the region.
Fraser-Smith originally thought there was something wrong with the equipment. After ruling out the possibility of technical malfunctions, he and his research team started to think the quake had quietly announced its impending arrival, and that their equipment just happened to be in the right place at the right time to pick up the message.
"Most scientists necessarily make measurements on small earthquakes because that's what occurs all the time," said Fraser-Smith. "To make a measurement on a large earthquake you have to be lucky, which we were," he added.
Fraser-Smith continued to study the phenomenon of earthquakes emitting electromagnetic waves through a study funded by the U.S. Geological Survey (USGS).
Though the professor moved on to other things after USGS terminated the funding in 1999, he was recently drawn back into this issue by a local private company that wanted to use his methods to develop earthquake-warning systems.
"I took a new look at the measurements, concentrating entirely on large earthquakes, and all of a sudden I could see the forest through the trees " said Fraser-Smith.
He found three other studies describing electromagnetic surges before large earthquakes, just as he had found earlier. The earliest report was from the Great Alaska earthquake (M9.2) in 1964.
"Up until now, most of the focus for earthquake warnings and predictions has been on seismological studies, but no seismic measurements have ever shown this kind of warning before a big quake, " said Fraser-Smith.
This technique will probably only yield results for earthquakes of approximately magnitude 7 or higher, because background waves from the atmosphere will tend to mask any smaller signals.
"Every year, there are on average 10 earthquakes of magnitude 7 or higher around the world," said Fraser-Smith. "So within just a few years, you could potentially have 10 new measurements of electromagnetic waves before big quakes," he added.