DEMETER satellite observations of energetic particle prior to Chile earthquake

Abstract

The lithosphere activity during seismogenic process or occurrence of one earthquake may emit electromagnetic waves which propagate to ionosphere and radiation belt, then induce disturbance of electric and magnetic field and the precipitation of high energy charged particles induced by pitch angle scattering from interaction of wave and particle. This paper, based on the data detected by DEMETER satellite, presents the high energy charged particle burst (PB) with 4 to 6 times enhancement over the average value observed about ten days before Chile earthquake in the center of epicenter within longitude 10 degrees and Mc Ilwain L 0. 1. The obvious particle burst was also observed in the northern hemisphere mirror points conjugate of epicenter. The energy spectra of the PBs are different from average value within the first three months in 2010. At the same time, the disturbance of the VLF electric spectrum under 300 Hz and in 13 similar to 20 kHz frequency band in ionosphere over the epicenter detected by the DEMETER satellite are also observed in the same two orbits. Finally we calculated the coupling relation between the energy of PBs and frequency range of VLF electric spectrum disturbance by wave and particle cyclotron resonant interaction, then obtained the consistent result of observation and theoretical calculation. It is indicated that the PBs are indeed caused by VLF electromagnetic wave in ionosphere possibly transmitted from earth's surface or lithosphere, which is a typical wave and particle coupling event. Eliminating the possible origin of PBs including magnetic burst and solar activities, we think the PBs and VLF electric spectrum disturbance are likely to have a certain link with Chile earthquake.