On the North?South Asymmetry of Co?Seismic Ionospheric Disturbances During the 16 September 2015 Illapel M8.3 Earthquake

The Mw8.3 Illapel earthquake on 16 September 2015 induced ionospheric disturbances detected by Global Positioning System ground-based total electron content (TEC) observations, which display much stronger TEC perturbations above the northern region of epicenter than southern region. To investigate cause asymmetry, we extend Wave Perturbation—Global Ionosphere-Thermosphere Model from using a point source representing epicentral crustal movement to an extended including ground motion caused propagating seismic waves. modeling results reveal that average, 31% north-south asymmetry in perturbation magnitude is different strengths northward and southward epicenter, while remaining 69% attributed background state magnetic field. In particular, spatial variation density field inclination angle contributes comparably asymmetry.