Temporal and spatial analyses on seismo-electric anomalies associated with the 27 February 2010 M = 8.8 Chile earthquake observed by DEMETER satellite

This paper studies seismo-electromagnetic anomalies observed by the French satellite DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) during the 27 February 2010 M = 8.8 Chile earthquake. The nighttime electron density (N_e), electron temperature (T _e), ion density (N_i), ion temperature (T_i) and whistler counts (C_w) are investigated. A statistical analysis of the box-and-whisker method is applied to see if data of two or more groups under study are significantly different. A cross-examination of temporal variations before and after shows that N_e and N_i (C_w) increases (decreases) appear 10-20 days before the earthquake. A comparison of data over the epicenter and those over its reference area can be employed to discriminate the earthquake-related anomalies from global effects. Results prove that anomalous enhancements of N_e, N_i, and T_i occur specifically around the epicenter area. The intersection of the temporal and spatial results confirms that N_e and N_i are useful and sensitive detecting anomalous related to the 2010 M = 8.8 Chile earthquake.