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<SUB>e</SUB>), electron temperature (T<SUB>e</SUB>), ion density (N<SUB>i</SUB>), ion temperature (T<SUB>i</SUB>) and whistler counts (C<SUB>w</SUB>) 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<SUB>e</SUB> and N<SUB>i</SUB> (C<SUB>w</SUB>) 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<SUB>e</SUB>, N<SUB>i</SUB>, and T<SUB>i</SUB> occur specifically around the epicenter area. The intersection of the temporal and spatial results confirms that N<SUB>e</SUB> and N<SUB>i</SUB> are useful and sensitive detecting anomalous related to the 2010 M = 8.8 Chile earthquake.

Ho, Y. -Y.;Liu, J. -Y.;Parrot, M.;Pinçon, J. -L.
Natural Hazards and Earth System Sciences
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