Can Electric Signals in the Atmosphere Be Used to Predict Earthquakes?

January 6, 2016 | Joanne Kennell

The devastation following an earthquake in Japan
Photo credit: Hikaru Kazushime/Flickr (CC BY-SA 2.0)

New finding may explain mysterious lights and spinning compasses that sometimes precede earthquakes.

Scientists have been trying to figure out how to predict earthquakes for years, and most seismologists say that being able to predict them will occur somewhere between the distant future and never.  However, some scientists believe they may have found a new way to predict these destructive natural disasters — using electromagnetic anomalies.

Kosuke Heki, a geophysicist at Hokkaido University in Sapporo, Japan, spotted an increase in the electron content of the ionosphere above Tohoku roughly 40 minutes before the magnitude 9.0 earthquake struck in 2011.  Using GPS data, Heki continues to study the ionosphere’s response to earthquakes.

Heki was skeptical of electromagnetic precursors at first, however, he noticed similar signals before nine other major earthquakes.  He also found that the earlier the anomalies precede the event, the stronger the earthquake will be — convincing him that the two are somehow linked.

But the next question is what is creating these electromagnetic signals?  One idea is that rocks generate positive charges when they are stressed.  According to Friedemann Freund, senior scientist at NASA’s Ames Research Center in Mountain View, California, “When you stress a rock, it turns into a battery. Not an electrochemical battery that you find in your car, but a new type of semiconductor battery that produces electrons and holes.”  

And the faster you stress them, the more electricity becomes available — which may be able to explain the strange events often reported before an earthquake, such as mysterious lights coming from the ground, compass needles spinning round and round, and maybe even the ionospheric disturbances that Heki is studying.

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Freund and John Scoville, a physicist at San Jose State University and the SETI Institute, have shown that rocks have a semiconducting behavior when they experience stress.  However, the electromagnetic pulses created in their tests are shorter and weaker than those observed before earthquakes.  However, that may be due to differences in scale: a 90-kilogram mass compared to an entire fault line.

There are still many seismologists that remain skeptical, including Tom Jordan, the director of the Southern California Earthquake Center in Los Angeles.  “We concluded that there was no evidence that ionospheric or electromagnetic precursors provide any diagnostic information about earthquakes in advance,” Jordan said.

Not only that, the majority of seismologists do not think Earth’s crust undergoes many changes before it ruptures that would produce precursor signals, and it is also not clear that the signals would indicate the size of an impending earthquake — the most important part.

Michael Blanpied, with the USGS Earthquake Hazards Program, thinks it’s unlikely that electromagnetic signals — or any other precursors — will turn out to be “a smoking gun.”  However, the idea should not be abandoned.  Not until researchers collect a lot more data.  “It may be that earthquakes are predictable only at a very, very marginal level,” he said.  Meaning the more data the better.

It is definitely an area of research worth pursuing.  Not only in the name of science, but also for its potential to save lives from devastating earthquakes.

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