Study of the variations in the Schumann resonances parameters measured in a southern Mediterranean environment

How Effective and Prerequisite Are Electromagnetic Extremely Low Frequency (ELF) Recordings in the Schumann Resonances Band to Function as Seismic Activity Precursors

ELF recordings, especially in the 0–50 Hz range (Schumann Resonances), have gained great interest during the last twenty years because of their possible relation to many geophysical, climatological, solar, and even biological phenomena, which several well-known scientists have reported. A very important question that still has not been answered is whether some particular variations in the Schumann Resonances (SR) band operate as precursors of forthcoming seismic activity. Greece and the wider Mediterranean area are a very seismic territory where medium size earthquakes (4–6.5 Richter) occur very often, contributing to a high percentage of the natural hazards of the area. In our effort to make evident how effective and prerequisite SR recordings are in the detection of forthcoming earthquakes, we analyze data collected for almost five years by two SR stations located in the north and the south edge of the Greek territory, respectively. We have come to the conclusion that particular SR modulations are very useful in the predictability of forthcoming seismic activity, but they need to be completed with additional observations of adjoining effects which can contribute to the final decision.

Correlation of local lightning activity with extra low frequency detector for Schumann Resonance measurements

A dedicated extremely low frequency (ELF) detector has been constructed and used successfully for Schumann Resonance (SRs) measurements in N.W. Greece. The main objective of this work was to investigate the effect of local lightning activity on the signal of our ELF detector and consequently on the estimated SRs parameters, namely the power, the frequency and the quality factor of each mode. Therefore, several measurements were taken into account for the ELF signal continuously recorded and the lightning intensity in a specific range around the ELF detector. Additionally, a simple filtering technique was used, in order to reject the distorted SRs spectra. The statistical analysis performed showed a positive and statistically significant correlation between the lightning events and the recorded magnetic component of the ELF signal. It was found that local lightnings have a significant impact on the SRs measurements, and it is necessary to be removed from the background signal.