Earthquake precursory signatures in electromagnetic radiation measurements in terms of day-to-day fractal spectral exponent variation: analysis of the eastern Aegean 13/04/2017–20/07/2017 seismic activity

• Published in: Journal of seismology Vol. 22; no. 6; pp. 1499 - 1513
• Main Authors: Cantzos, Demetrios, Nikolopoulos, Dimitrios, Petraki, Ermioni, Yannakopoulos, Panayotis, Nomicos, Constantinos
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.11.2018; Springer Nature B.V
• Subjects: Earth and Environmental Science; Earth Sciences; Earthquake prediction; Earthquakes; Electromagnetic radiation; Evolution; False alarms; Fractal analysis; Frequencies; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Original Article; Radiation; Radiation measurement; Seismic activity; Seismology; Signatures; Structural Geology; Variation; Radiation monitoring; Fractal analysis; Remote sensing; Earthquake precursors
• ISSN: 1383-4649; 1573-157X
• DOI: 10.1007/s10950-018-9781-6

The recent seismic activity in the eastern Aegean Sea, foregrounded by two major ( M L  = 6.1 and M L  = 6.2) earthquakes occurring near Lesvos and Kos islands, respectively, is investigated in this work. Electromagnetic radiation measurements across different frequency bands and antenna orientations from a monitoring station in Agia Paraskevi, Lesvos Island, are analysed in order to reveal earthquake precursory signatures hidden in the electromagnetic data sequence. A straightforward, data-driven approach is employed in which day-to-day variations of the fractal characteristics of the measurements are adaptively monitored via a fractal spectral exponent similarity measure. The evolution of the fractal day-to-day variation in a 99-day period, which includes the two major earthquakes, shows a sustained, sudden increase lasting 1 to 4 days before every earthquake cluster of M L  = 4.0 and above. Most importantly, this day-to-day variation subsides shortly after and remains relatively low during the absence of earthquakes, thus alleviating the emergence of false alarms.