Variations of the Geomagnetic Field before the 6.2-Magnitude Earthquake of Central Italy in 2016

Abstract

Summary In this paper, we aim at exploring how geomagnetic field components may change prior to earthquakes. We used the datasets recorded in Duronia, Lampedusa, and Castello Tesino geomagnetic observatories, available online by Istituto Nazionale di Geofisica e Vulcanologia (INGV). Variations of magnetic field components were studied before the 6.2-magnitude earthquake that hit the central Italy on 24 August 2016. The results showed anomalous changes in the geomagnetic field before the earthquake. Variations occurred from about three hours before the earthquake and continued for the day after. Analysis of data in the frequency domain showed that these variations occurred in the Ultra-low frequency (ULF) range. Consistent trends observed in datasets of the three observatories could be an indication of proper operation of the instruments and adequate accuracy of the datasets. Kp index showed calm geomagnetic days for the time period of changes which might be caused by the earthquake. Therefore, the variations observed in the short-time before the earthquake could be correlated to the earthquake activity. Variations of the geomagnetic field within the ULF range can be interesting to be more investigated as one of the earthquake precursors.