Investigation of anomalous perturbations in VLF signals and correlation with seismic activity

Prior to earthquakes anomalous perturbations in the ionosphere have either been observed as fluctuations in the F-region critical frequency, foF2, or as deviations in VLF signals. Such phenomena have been recorded up to 6 days before the main shock, making their identification imperative in aiding in earthquake prediction. However, a lack of reproducibility of the events and the large scale effect of solar activity on the ionosphere, isolation of seismogenic signals is difficult. Using narrowband receiver data from Hungary, VLF waves are analyzed to investigate the presence of anomalous perturbations, which are then correlated with seismic activity.