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"Swamp gas?"
Mulder, F.W. in the “X-Files ” (1993)
Summer is traditionally Silly Season, when newspapers publish strange stories about aliens and monsters again and again to bridge holiday time – and so will July on “History of Geology” be dedicated to frivolous science stories…
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Earthquake Lights - or short EQLs - seem to be old phenomena. Irish engineer and amateur seismologist Robert Mallet published in 1851-1855 a catalog, where he dated back EQLs to biblical times, interpreting descriptions of fire-columns in the bible as early misidentifications of EQL. The Italian priest and amateur naturalist Ignazio Galli (1841-1920) published in 1910, based on a collection of events from ten centuries, a first classification scheme of EQLs. In his book "Raccolta e classificazione dei fenomeni luminosi osservati nei terremoti" (Collection and Classification of luminous phenomena observed during earthquakes) he recognizes four categories: short-lasting diffuse lights, long-lasting diffuse lights, flames and luminescent clouds and finally moving lights (globes and columns). He also notes that the different categories show different temporal patterns, short-lasting lights like flashes occur mostly before a quake, clouds and orbs during a quake and flames after an event. However nobody could explain the origin of these apparitions. One of the most plausible hypothesis at the time, proposed by Italian seismologist Giovanni Ciuseppe Bianconi in 1840, explained the lights as burning gas, emanating from fissures opening during a quake. However burning gas could explain only small flames, not large-scale glowing clouds.
Today's working hypotheses consider electromagnetic effects behind EQLs; this could also explain reports of malfunctions of electric devices (especially telephones) during such events. Electric charges can accumulate over time during the tectonic deformation of rocks, during an earthquake this electric energy is suddenly released in form of a visible spark. EQLs could also be a sort of glowing gas, formed by the ionizing properties of some rocks.
Some researchers made even a connection of EQLs to another, supposedly unexplained phenomenon - Unidentified Flying Objects, in short UFOs. In 1977 the psychologists Michael A. Persinger and Ghislaine Lafreniere published the book "Space-Time Transients and Unusual Events", arguing that UFOs are misidentified electric sparks caused by accumulating telluric-electric charges. Going a step further, some UFOlogists speculated that the generated electric fields are strong enough to influence a bystander´s mind and cause hallucinations. To support their hypothesis the authors tried to correlate UFOs sightings with the seismic zones in the U.S., however there seems to be also a high correlation with booze consumption...
Fig.2. UFOs, UFOs everywhere .... simplified map with seismic activity in the United States and supposed areas of increased UFOs sightings in 1870-1960, modified after PERSINGER.