Enhanced ULF radiation observed by DEMETER two months around the strong 2010 Haiti earthquake

M. A. Athanasiou,C. N. David,A. C. Iliopoulos,G. P. Pavlos,G. C. Anagnostopoulos

doi:10.5194/nhess-11-1091-2011

M. A. Athanasiou, C. N. David + Show 3 more

Open Access

https://doi.org/10.5194/nhess-11-1091-2011

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Abstract

Abstract. In this paper we study the energy of ULF electromagnetic waves that were recorded by the satellite DEMETER, during its passing over Haiti before and after a destructive earthquake. This earthquake occurred on 12 January 2010, at geographic Latitude 18.46° and Longitude 287.47°, with Magnitude 7.0 R. Specifically, we are focusing on the variations of energy of Ez-electric field component concerning a time period of 100 days before and 50 days after the strong earthquake. In order to study these variations, we have developed a novel method that can be divided in two stages: first we filter the signal, keeping only the ultra low frequencies and afterwards we eliminate its trend using techniques of Singular Spectrum Analysis (SSA), combined with a third-degree polynomial filter. As it is shown, a significant increase in energy is observed for the time interval of 30 days before the earthquake. This result clearly indicates that the change in the energy of ULF electromagnetic waves could be related to strong precursory earthquake phenomena. Moreover, changes in energy associated with strong aftershock activity were also observed 25 days after the earthquake. Finally, we present results concerning the comparison between changes in energy during night and day passes of the satellite over Haiti, which showed differences in the mean energy values, but similar results as far as the rate of the energy change is concerned.

Highlights

Earthquakes (EQs) are complex phenomena generated by rock deformation in the brittle outer part of the Earth and are associated with large unpredictability, due to inherent extreme randomness (Kagan, 2007)
In this study we have focussed on changes in the energy of electromagnetic ULF waves (0–20 Hz) of the electric field component Ez that were recorded by the satellite DEMETER, concerning a time period of 100 days before and 50 days after a strong earthquake which took place in Haiti in 12 January 2010
The analysis was based on a novel method consisted of two stages: first, the signals were filtered keeping only the very low frequencies, and consecutively their trend was eliminated by applying the techniques of Singular Spectrum Analysis combined with a third-degree polynomial filter

Summary

Introduction

Earthquakes (EQs) are complex phenomena generated by rock deformation in the brittle outer part of the Earth and are associated with large unpredictability, due to inherent extreme randomness (Kagan, 2007). (5) The amount of ULF data (much less than the corresponding ELF/VLF data) is suitable for analysis in the time domain as well as for the application of Singular Spectrum Analysis (6) significant emissions have been found in the range of ∼50 Hz (Blecki et al, 2010b), which are close to the range of the ULF scale (0–20 Hz). For these reasons, we chose to focus on space-based ULF EM emissions to study their energy changes during a long period before and after a strong EQ. Our study was based on the analysis of measurements from the DEMETER satellite around the deadly earthquake of Haiti on 12 January 2010

Data analysis and results

Findings

Conclusions