Development Of A Fdtd Simulation Of Ionosphere Propagation For Earthquake Precursor Over The Sumatera-Malaysia Region

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Date
2018-09
Authors
Siti Harwani Md Yusoff
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Publisher
Universiti Sains Malaysia
Abstract
The perturbation on the vertical electric field in the ionosphere before large the large earthquake is a poorly investigated problem. The information obtaining from the electromagnetic (EM) wave propagated through the ionosphere can be applied to construct an earthquake precursor. This study conducted through the development of a home-grown 2D Finite Difference Time Domain (FDTD) code to simulate the EM propagation in the anisotropic ionosphere. To imitate the anisotropic and dispersive condition of the ionosphere, the electron density (𝑁𝑒) profile collected from the CHAMP satellite is applied in the code as the medium parameter. The data used in this code is from 5 days before Aceh 2004 Andaman Sea earthquake, occurred on 26th December 2004. Perfectly Matched Layer (PML) as an absorbing boundary condition is implemented in the code to ensure minimum wave reflected from the boundary of the computational grid. Based on data generated from the FDTD simulation, a protocol for an earthquake precursor, known as Δ𝑄 is constructed. As results, some perturbations in electron density profile are observed 3 days before the large earthquake occurred, shown in the high value of 𝑁𝑒 in the profile. In addition, a day shows a distorted profile. The vertical electric field from EM propagation using FDTD simulation is developed and shows good sensitiveness to the change of the medium in the ionosphere. The PML efficiency is measured through the relative error calculation. The results show 25 cells of PML can suppress the reflective wave 48% better than 5 cells of PML. Due to the lack of data on 𝑁𝑒, no conclusive prediction can be drawn from the measurement of Δ𝑄. However, the feature of Δ𝑄 plot alone hinted a peak before at the occurrence of the earthquake. As a conclusion, it is technically viable to couple ionospheric parameter into the computational electromagnetic simulation as an attempt to develop an earthquake precursor.
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Keywords
Radio wave propagation , Earthquake prediction
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