A while back, I wrote about a paper that appeared in the Journal of Zoological Douchery - or some such - where the authors reported that all the toads in an entire swamp had mysteriously disappeared just prior to the 2009 L'Aquila earthquake in Italy. Said authors had traveled to Italy to study said toads and were somewhat "annoyed" to discover that there were no toads to study. So to justify their stay on the Italian Riviera, said authors wrote a "paper" on the fact that there were no toads there because the toads had cleared out prior to the earthquake and ascribed this disappearance to a disturbance in the ionosphere or some such nonsense.
I don't doubt that this mysterious toad disappearance has continued to bother most people. Why did the toads leave? Are they okay? Are extraterrestrials involved? Can we blame it on global warming? (This last from noted thinker, Al Gore) After all, we can't just have toads disappearing without explanation. Fortunately, this month's Geology magazine has come to the rescue and shed some light on this mystery. A paper by Toshiko Terakawa used focal mechanism tomography - read "a way to let us publish awesome looking 3-D color pictures in our article" - to infer that the L'Aquila earthquake was caused by high pressure carbon dioxide infiltrating into the fault zone. This infiltration had the effect of lubricating the fractured rock surfaces, causing them to slip. Dr. Terakawa notes that the infiltration was accompanied by a "diffuse degassing." In other words, a great deal of carbon dioxide was seeping up out of the ground in the days prior to the earthquake. One might imagine that with all this carbon dioxide coming out of the ground, life down at toad level might have become generally unpleasant...not only is it getting hard to breathe, but your favorite swamp water is slowly turning into one big Scotch and soda minus the Scotch.
In a second paper in the same issue of Geology, Francesco Pio Lucente presents his analysis of the 188 foreshocks that preceded the main earthquake. Dr. Lucente's analysis is not particularly relevant here, but note: There were 188 small earthquakes leading up to the main event. So, imagine if you will, you're a toad living in the L'Aquila toad swamp when the whole place starts jiggling like a Jello mold on a folding card table. I suspect that to whatever degree the toad brain can conceptualize "This sucks" it did and they cleared out to more stable - and breathable - swamp land.
Mystery solved. You're welcome.