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