Investigation of GIM-TEC disturbances before M ≥ 6.0 inland earthquakes during 2003–2017

Abstract

With the rapid development of the Global Navigation Satellite System (GNSS) and its wide applications to atmospheric science research, the global ionosphere map (GIM) total electron content (TEC) data are extensively used as a potential tool to detect ionospheric disturbances related to seismic activity and they are frequently used to statistically study the relation between the ionosphere and earthquakes (EQs). Indeed, due to the distribution of ground based GPS receivers is very sparse or absent in large areas of ocean, the GIM-TEC data over oceans are results of interpolation between stations and extrapolation in both space and time, and therefore, they are not suitable for studying the marine EQs. In this paper, based on the GIM-TEC data, a statistical investigation of ionospheric TEC variations of 15 days before and after the 276 M ≥ 6.0 inland EQs is undertaken. After eliminating the interference of geomagnetic activities, the spatial and temporal distributions of the ionospheric TEC disturbances before and after the EQs are investigated and compared. There are no particularly distinct features in the time distribution of the ionospheric TEC disturbances before the inland EQs. However, there are some differences in the spatial distribution, and the biggest difference is precisely in the epicenter area. On the other hand, the occurrence rates of ionospheric TEC disturbances within 5 days before the EQs are overall higher than those after EQs, in addition both of them slightly increase with the earthquake magnitude. These results suggest that the anomalous variations of the GIM-TEC before the EQs might be related to the seismic activities.

Investigating short-term earthquake precursors detection through monitoring of total electron content variation in ionosphere

“…Both light and moderate earthquakes showed only 2% occurrences each in terms of total precursors found (Figure 1). Kon et al (2011) and Zhu and Jiang (2020) concur that the frequency of ionospheric TEC disturbances is directly proportional to the magnitude of the earthquake. Hence, as the magnitude of the earthquake increases, any slight rise in the occurrence rates of TEC disturbances preceding the event is more likely to be associated with the impending seismic activity (Pulinets et al, 2003).…”

Singular Spectrum Analysis of the Total Electron Content Changes Prior to M ≥ 6.0 Earthquakes in the Chinese Mainland During 1998–2013

“…If the earthquake samples are analyzed together, one may not find clear results as the correlation between either negative or positive anomalies and earthquakes will decrease. This might be the reason why no significant anomalies for global earthquakes were detected in some studies (Zhu and Jiang, 2020). In addition, the RMS of GIM-TEC data is different at different places due to the uneven distribution of GPS stations.…”

GNSS TEC-Based Earthquake Ionospheric Perturbation Detection Using a Novel Deep Learning Framework

“…They found that the anomalies were concentrated 1-5 days before the earthquakes and that the anomalies were most obvious near the epicenter. In similar research, Zhu and Jiang [18] statistically investigated ionospheric TEC variations 15 days before and after 276 individual inland earthquakes of M s ≥ 6.0. After excluding the disturbance of geomagnetic activity, they found differences in terms of spatial distribution, with the largest differences being in the epicentral region, whereas the incidence of ionospheric TEC disturbances in the five days before each earthquake was generally higher than that after the earthquake, and both increased slightly with the magnitude.…”