From the Triple-A-S - American Association for the Advancement of Science:
Can electric signals in Earth’s atmosphere predict earthquakes?
Ask seismologists when they’ll be able to predict earthquakes, and the answer is generally: sometime between the distant future and never. Although there have been some promising leads over the years, the history of earthquake forecasting is littered with false starts and pseudoscience. However, some scientists think that Earth’s crust may give hints before it ruptures, in the form of electromagnetic anomalies in the ground and atmosphere that occur minutes to days before an earthquake. Last week, here at the fall meeting of the American Geophysical Union, researchers shared their evolving understanding of these phenomena—and how they might be used to predict deadly quakes.
Kosuke Heki, a geophysicist at Hokkaido University in Sapporo, Japan, first got interested in the subject when he spotted an increase in the total electron content of the ionosphere—the charged outermost layer of the atmosphere—above Tohoku about 40 minutes before the magnitude 9.0 earthquake struck in 2011. Heki had long used GPS data to study ionospheric responses to earthquakes, which occur when the sudden movement of Earth’s crust reverberates through the atmosphere. Ionospheric disturbances interfere with the communication between GPS satellites and receivers, leaving a fingerprint at specific radio frequencies that researchers can tease out.
In 2011, Heki was skeptical of electromagnetic precursors. But since then, he has used the world’s growing array of GPS stations to identify similar signals before nine other major earthquakes, he explained at the meeting. In addition, Heki has found that earlier anomalies precede stronger earthquakes, potentially reflecting the longer time needed to initiate rupture along larger segments of a fault. Now, he says he’s convinced there’s really something going on: “Seeing is believing.”
I love the serendipitous nature of his work - a completely different network built for a completely different task and this guy is able to find valid data embedded in the noise.
Some kinds of rocks exhibit piezoelectricity when mechanically deformed (your clicky butane lighter is a perfect example), some others triboelectricity (scuffing your feet on the carpet and touching someone). Both of these can develop a very high voltage which can be picked up with sensitive instrumentation. Our atmosphere is a fascinating conductor of electricity as any radio operator will well know...
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