Detection of ionospheric disturbances driven by the 2014 Chile tsunami using GPS total electron content in New Zealand

A tsunami propagating in open ocean can produce gravity waves and thus perturb the ionosphere. In this study, we employ a second-order numerical difference method using GPS total electron content observed in New Zealand to detect the ionospheric disturbances triggered by the Chile tsunami that occurred on 1 April 2014. We observe traveling ionospheric disturbances (TIDs), which have similar horizontal velocity and direction as the tsunami waves, at different times after the event. According to the arrival times, the latter TIDs (about 14.5-15h after earthquake) can be attributed to the tsunami waves whereas the former one (about 12h 30min after earthquake) could be related to other sources. This suggests that besides the propagation velocity and direction, the arrival time is also necessary to distinguish tsunami-driven TIDs correctly. Furthermore, we observe the phenomenon that the detected tsunami-driven TIDs are superimposed upon other nontsunami-driven ionospheric perturbations far away from the epicenter. The superimposed TIDs eventually separate due to their different propagation velocities.