Simulating the dependence of seismo-ionospheric coupling on the magnetic field inclination

Infrasound generated during a seismic event upon reaching the ionospheric heights possesses the ability to perturb the ionosphere. Detailed modelling investigation considering 1-D dissipative linear dynamics, however, indicates that the magnitude of ionospheric perturbation strongly depends on the magnetic field inclination. Physics-based SAMI2 model codes have been utilized to simulate the ionosphere perturbations that are generated due to the action of the vertical wind perturbations associated with the seismic infrasound. The propagation of the seismic energy and the vertical wind perturbations associated with the infrasound in the model has been considered to be symmetric about the epicentre in the north–south directions. Ionospheric response to the infrasound wind, however, has been highly asymmetric in the model simulation in the north–south directions. This strong asymmetry is related to the variation in the inclination of the Earth's magnetic field north and south of the epicentre. Ionospheric monitoring generally provides an efficient tool to infer the crustal propagation of the seismic energy. However, the results presented in this paper indicate that the mapping between the crustal process and the ionospheric response is not a linear one. These results also imply that the lithospheric behaviour during a seismic event over a wide zone in low latitudes can be estimated through ionospheric imaging only after factoring in the magnetic field geometry.