Long-Memory Trends in Disturbances of Radon in Soil Prior to the Twin ML=5.1 Earthquakes of 17 November 2014 Greece

Nikolopoulos D, Petraki E, Nom

Abstract

On 17 November 2014, at 23:05 and 23:09 local time, two shallow earthquakes of ML=5.1 occurred in Prokopion, Chalkis, 86 km North-West of Athens, Greece. Prior to the earthquakes a significant radon anomaly was observed by a telemetric radon station operating with a Barasol MC2 probe (Algade France). The anomaly lasted approximately between 24 Oct 2014 and 10 November 2014. This paper reports the trends of long-memory that were addressed through Rescaled Range (R/S) analysis and Detrended Fluctuation Analysis (DFA). Hurst exponents above 0.8 were found by R/S analysis during the radon anomaly. The signal exhibited persistent behavior. DFA verified the findings of R/S analysis within the anomaly.