Abstract
We present a comprehensive analysis of pre-seismic anomalies as computed from the ground and space-based techniques during the recent Samos earthquake in Greece on 30 October 2020, with a magnitude M = 6.9. We proceed with a multi-parametric approach where pre-seismic irregularities are investigated in the stratosphere, ionosphere, and magnetosphere. We use the convenient methods of acoustics and electromagnetic channels of the Lithosphere–Atmosphere–Ionosphere-Coupling (LAIC) mechanism by investigating the Atmospheric Gravity Wave (AGW), magnetic field, electron density, Total Electron Content (TEC), and the energetic particle precipitation in the inner radiation belt. We incorporate two ground-based IGS GPS stations DYNG (Greece) and IZMI (Turkey) for computing the TEC and observed a significant enhancement in daily TEC variation around one week before the earthquake. For the space-based observation, we use multiple parameters as recorded from Low Earth Orbit (LEO) satellites. For the AGW, we use the SABER/TIMED satellite data and compute the potential energy of stratospheric AGW by using the atmospheric temperature profile. It is found that the maximum potential energy of such AGW is observed around six days before the earthquake. Similar AGW is also observed by the method of wavelet analysis in the fluctuation in TEC values. We observe significant energetic particle precipitation in the inner radiation belt over the earthquake epicenter due to the conventional concept of an ionospheric-magnetospheric coupling mechanism by using an NOAA satellite. We first eliminate the particle count rate (CR) due to possible geomagnetic storms and South Atlantic Anomaly (SAA) by the proper choice of magnetic field B values. After the removal of the statistical background CRs, we observe a significant enhancement of CR four and ten days before the mainshock. We use Swarm satellite outcomes to check the magnetic field and electron density profile over a region of earthquake preparation. We observe a significant enhancement in electron density one day before the earthquake. The parameters studied here show an overall pre-seismic anomaly from a duration of ten days to one day before the earthquake.
Highlights
The seismic hazards and their preparation mechanism are extremely complex
We summarize the methodology applied for the extraction of the Atmospheric Gravity Wave (AGW) from the SABER temperature profile
The diurnal variation of Vertical Total Electron Content (VTEC) from 17 October to 4 November 2020, with the upper and lower bound are shown in the upper panel of Figure 3 for the DYNG station
Summary
The seismic hazards and their preparation mechanism are extremely complex. The overall mechanism and its possible outcomes have huge outbursts of mechanical energy but have a wide range of physical and chemical processes attached to the lithosphere, atmosphere, and ionosphere [1]. It is found that the pre-EQ processes are nonlinear, anisotropic, and can have a dependency of multiple parameters Based on such an idea, a coupling mechanism was established to understand the pre-seismic process that begins well before the mainshock known as the Lithosphere–Atmosphere–Ionosphere coupling (LAIC) mechanism [1]. This coupling (LAIC) mechanism is detected through various channels such as thermal [1], acoustic [21,22], and electromagnetic [23]. The anomalies are observed using ground-based observations with the Very-Low-Frequency (VLF)/Low frequency (LF) radio wave, Critical frequency of F2 layers ( f 0F2 ), Total Electron Content (TEC), Ultra
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
