The enormous economic and social disruption caused by large earthquakes drives many researchers toward the goal of better seismic understanding, with the hope of improving the forecasting of destructive events. A 2006 Eos article describes preseismic “lithosphere-atmosphere-ionosphere coupling” [Kamogawa, 2006], giving the strong impression that the ionospheric signatures could indeed be used to provide early warning of imminent shocks. On the basis of the literature discussed in the article, this would indeed be true.
In many of the cases outlined, however, the high correlations described occur in small case studies, and no mention is made of follow-on statistical studies that have drawn totally opposite conclusions, i.e., that the proposed coupling does not exist. Two clear examples come from the description of earthquake precursors reported in the propagation behavior of very low frequency (VLF) electromagnetic waves beneath the lower ionosphere.