Imagine how many lives would be saved if the atmosphere could detect a major earthquake 30 or minutes before it rocked the land beneath. Japanese researcher Kosuke Heki believes he may have identified such a precursor: electron counts 185 miles high in the sky, in the atmospheric layer known as the ionosphere. His research, published in the journal Geophysical Research Letters, shows ionospheric electron counts unexpectedly escalated beginning 40 minutes before Japan’s deadly March 11 quake.
Measurements gleaned from GPS satellites recorded more electrons in the ionosphere over the soon-to rupture fault than expected. A similar uptick occurred before extra-large quakes in Chile in 2010 and Sumatra in 2004, the researcher found.
Such an atmospheric-geologic connection would no doubt be groundbreaking. But a key question emerging from this research, as Heki the author acknowledges, is: Could the electron increase observed prior to recent large quakes have resulted from a different phenomena like solar flares?
Until this question can be resolved, some geologists are reserving judgment on the significance of the study.
“This could potentially be something really cool or simply a coincidence,” said Callan Bentley, professor of geology at Northern Virginia Community College and author of the blog Mountain Beltway.
Bentley said he’d like to see further monitoring of these electron counts and a plot with more data points that better establishes the relationship. Even then, he’d want to understand physical connection between the earthquake and the atmosphere.
“If there is a strong correlation, what’s the causative mechanism?” he said.
AGU’s Geospace blog interviewed Hiroo Kanamori, a professor emeritus of geophysics at the California Institute of Technology, who expressed similar sentiments to Bentley:
“I think it’s worthwhile to document it like this, to see what will happen with the next event,” Kanamori says, “but I can’t be completely convinced.”
Even if a link between electron counts and large earthquakes was firmly established, the Geospace blog notes the time required to analyze the data would preclude using these counts to predict earthquakes before they happen, at least right now:
It’s currently not feasible to use total electron content as a warning system for giant quakes, Heki says. There is a dense network of GPS satellites, especially over earthquake-prone areas like Japan, California and Indonesia, but the organization running the GPS network over Japan uploads the data once every few hours. And it takes time to analyze the data and weed out other disturbances to the total electron content like solar flares.
Heki’s research has not identified electron count increases for small earthquakes.