Possible electromagnetic earthquake precursors in two years of ELF-VLF monitoring in the atmosphere

Abstract

In this study we show that ELF-VLF emissions, occurred during the fracturing of rocks in laboratory experiments and during rock extraction in a cave, have been recorded also before earthquakes by 3 ELF-VLF stations installed in the central Apennines. The electric field emission is composed by two types of signals which are related to the evolution of micro-fractures within the rocks. During two years of monitoring, from August 2003 to September 2005, we recorded three signals, which all have frequency band and characteristics similar to the signal recorded during the fracturing of rocks in the laboratory and during the extraction of rocks. All these signals occurred a few days before the occurrence of M ≥ 4.5 earthquakes in the surrounding region (100-300 km). May be EM precursors of the earthquakes ?