Novelty detection in time series of ULF magnetic and electric components obtained from DEMETER satellite experiments above Samoa (29 September 2009) earthquake region

M Akhoondzadeh

doi:10.5194/nhess-13-15-2013

Abstract

Abstract. Using ULF (ultra low frequency) measurements of magnetometer and ICE (Instrument Champ Electrique) experiments on board the DEMETER satellite, possible irregularities in ULF magnetic and electric components have been surveyed in the vicinity of Samoa (29 September 2009) earthquake region. The data used in this paper cover the period from 1 August 2009 to 11 October 2009. The anomalous variations in magnetic components (Bx, By and Bz) were clearly observed on 1 and 3 days before the event. It is seen that the periodic patterns of the magnetic components obviously changed prior to the earthquake. These unusual variations have been also observed in the variations of polarization index obtained from the magnetic components during the whole period at ~10:30 and ~22:30 LT. It is concluded that the polarization exhibits an apparent increase on 1 and 3 days preceding the earthquake. These observed unusual disturbances in ULF magnetic components were acknowledged using the detected perturbations in ULF electric components (Ex, Ey and Ez) in the geomagnetic coordinate system. Finally, the results reported in this paper were compared with previous results for this Samoa earthquake. Hence, the detected anomalies resulting from the magnetometer and ICE ULF waveforms in quiet geomagnetic conditions could be regarded as seismo-ionospheric precursors.

Highlights

The pre-seismic perturbations in lithosphere, atmosphere and ionosphere without significant solar and geomagnetic disturbances are considered as earthquake precursors
It can be seen the wave forms of ULF electric components (Ex, Ey and Ez) that the selected section in the time series has similar vari- measured by ICE experiment on board the DEMETER satelations in the dotted ellipsoids 1 through 3, but it suddenly lite close to the Samoa seismic region from about 54 days changes in the dotted ellipsoid 4
Results of DEMETER data analysis for the Samoa earthquake (29 Septem direction of X. (b) V ×B electric field component in direction of X. (c) ICE ULF waveform without induced V ×B electric field in direction of X

Summary

Introduction

The pre-seismic perturbations in lithosphere, atmosphere and ionosphere without significant solar and geomagnetic disturbances are considered as earthquake precursors. Panels (a) through (c) represent the geographic variations of the magnetic components Bx, By and Bz, respectively, for the Samoa earthquake (29 September 2009) from 1 August to 31 October 2009 .

Results

Conclusion