Irregularities of the ionospheric plasma and the ULF electric components obtained from DEMETER satellite experiments abo
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ORIGINAL PAPER
Irregularities of the ionospheric plasma and the ULF electric components obtained from DEMETER satellite experiments above Chile earthquake (27 February 2010) Soraya Louerguioui & Said Gaci & Naima Zaourar
Received: 5 December 2013 / Accepted: 2 April 2014 # Saudi Society for Geosciences 2014
Abstract The detection of ionospheric disturbances associated with seismic activity is one of the main purposes of the Detection of Electromagnetic Emissions Transmitted from Earthquake Regions (DEMETER) micro-satellite. In this view, this study attempts to analyze the problem of detecting these disturbances before an earthquake occurrence and to discuss the Chile earthquake case study. Using ultralow frequency (ULF) measurements of Instrument Champ Electrique (ICE) experiments on board the DEMETER satellite, possible irregularities in this electric component have been investigated in the vicinity of Chile (27 February 2010) earthquake region. The data used in this paper cover the period from 10 to 26 February 2010. The anomalous variations in the calculated ULF electric component in the direction Z of satellite were clearly observed on the 17th, 11th, and 1st days preceding the earthquake. It is noted that the electric component obviously strongly decreased prior to the earthquake. These unusual variations have also been observed in the variation of several plasma parameters recorded by DEMETER directly above the epicenter during the whole period. Hence, the detected anomalies resulting from the ICE ULF waveforms in quiet geomagnetic conditions could be regarded as seismo-ionospheric precursors.
S. Louerguioui : N. Zaourar Geophysics Department-FSTGAT, University of Sciences and Technology Houari Boumediene (USTHB), BP 32 El Alia, 16111 Algiers, Algeria S. Louerguioui e-mail: [email protected] N. Zaourar e-mail: [email protected] S. Gaci (*) Sonatrach, Division Exploration, Boumerdès, Algeria e-mail: [email protected]
Keywords DEMETER . Preseismic . Electric field . ULF . Ionosphere
Introduction In the last 20 years, a number of papers reported the detection of natural electromagnetic signals related to the Earth’s seismic activity, mainly not only from ground-based receivers but also from satellite experiments. The corresponding observations cover a wide range of frequencies with measurements gathered at ultralow frequency (ULF) (Fraser-Smith et al. 1990; Molchanov et al. 1992; Hayakawa et al. 2000; Zhang et al. 2011), extremely low frequency (ELF) and very low frequency (VLF) (Molchanov et al. 1993; Singh et al. 2000, see also reviews by Molchanov et al. 1993; Hayakawa 1997), low frequency (LF) and high frequency (HF) (Biagi 1999; Takano et al. 2002), and even recently in the very high frequency (VHF) range (Yamada et al. 2002; Berthelier et al. 2006). The analysis of a possible relation of ULF waves in the upper ionosphere with earthquakes using satellite data is in its infancy, and limited researches in this topic can be found in literature. In this view, we suggest in this paper an investigatio
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