Precursory Anomaly in VLF/LF Recordings Prior to the Çaglayan (Erzincan-Turkey) Earthquake on July 30th, 2009

Abstract

An international project network consisting of six receivers for sampling LF and VLF radio signals has been going on to record the data in Europe from different transmission stations around the World. One of them was established in Resadiye, Turkey, located just on the North Anatolian Fault Zone. The receiver works in VLF and LF bands monitoring ten frequencies (16.4, 21.75, 37.5, 45.9, 153, 180, 183, 216 and 270 kHz) with one minute sampling interval. An earthquake of Mw = 4.9 took place 225 km away from the VLF/LF station at the eastern tip of the Erzincan basin at 4 km depth on July 30, 2009. We observed some anomalies on the radio signals (37.5 and 153 kHz) that initiated about 7 days before the earthquake and disappeared soon after the earthquake. We attribute this anomaly to the Mw=4.9 earthquake as a seismo-electromagnetic precursor. The radio anomaly that appeared 7 days before the occurrence of the 2009 Caglayan (Erzincan) earthquake is in good agreement with other results indicating precursory anomalies in the project network mostly observed in seismically active countries such as Italy and Greece.