Analysis of pre-earthquake anomaly of ionosphere based on GPS

The ionosphere would exhibit precursors of abnormal disturbances before the earthquake. In the paper, Various factors influencing the ionospheric activi ty were analyzed. The ionospheric TEC data of the ionosphere before Mount Lu earthquake were extracted based on GPS, and the VTEC timing diagram and the global ionospheric anomaly map were drawn. Based on the time series, the ionospheric TEC anomaly perturbation of the global ionospheric grid data of Mount Lu earthquake was analyzed.The experiment found that the positive and negative anomalies of the ionospheric TEC of about 4 hours were observed two days before the earthquake.A nd the ionospheric TEC anomalies all appeared near the epicenter, the anomalous area moved westward with time, and the shape of the anomalous area was about the equator conjugation.