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VLF Waves, the Ionosphere, and Earthquakes - Space Weather Monitors

VLF Waves, the Ionosphere, and Earthquakes

There is some intriguing research about whether large earthquakes are associated with ionospheric changes caused by electromagnetic signals released by the crushing of rock crystalline structures. If so, then this might be a mechanism for major earthquake prediction.

One of the primary researchers in this area is Friedemann Freund, of NASA Ames. He has written several articles introducing the concept of ionospheric and atmospheric changes as earthquake precursors:

According to Freund, "Earthquake forecasters can also watch for changes in the ionosphere by monitoring very-low-frequency (3- to 30-kilohertz) and high-frequency (3- to 30-megahertz) radio transmissions. The strength of a radio signal at a receiver station changes with the diurnal cycle: it is greater at night than in daylight... The altitude of the ionosphere, which moves lower as the positive holes [positively-charged atoms in stressed rock] migrate to the surface, also has an effect on radio signals; the lower the ionosphere, the stronger the signals. So at dawn on an earthquake day, a curve drawn to represent the drop-off in radio signal strength will appear markedly different from the normal curve for that signal at that location." (Earthquake Predictor) That is, Fruend believes that the dawn-dusk signatures will be different for a particular instrument, perhaps even the signal strength as monitored during the day, on the day of a major earthquake.

Since the original papers, Freund has made further progress in understanding some of the more subtle physics underlying the generation of signals prior to major seismic events: "Those signals may serve as early warning signs. Of particular practical and theoretical interest is the emission of infrared photons from the ground. These photons are non-thermal but mix with the 300 K thermal IR emission bands." Their paper (also highlighted above) describes some rather unique laboratory experiments demonstrating this stimulated (quantum-controlled) IR emission.

This research is still young and apparently controverial. If there are effects, they may be too subtle for the SID instruments to pick up. If your students do pursue something of this nature, make sure you make it VERY clear to them that this is extremely early and tentative research that may or may not provide them any useful results.

If your students do want to explore this, remind them that the epicenter of a potential earthquake would have to lie somewhere "near" the line between the transmitter and their receiver. (And we have no idea what distances might qualify as "near.") Thus they would need to track data from all over the world and, if something irregular were noted, they would need to triangulate to determine the location of the potential earthquake. Best approach might be to pick a recent earthquake then check the SID data from stations around the world to see if any changes were noticed at, before, or after, that time.

In addition to the 3 above, here are more resource articles you might want to explore:

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