III. RESULTS AND DISCUSSION: Fig. 1 shows the map of part of Asia on which the stars indicate the location of earthquakes and the solid circle indicates the location of the Agra observation station (27.2o N, 78o E). The details of these earthquakes are mentioned in Table 1 which shows days of occurrence, magnitudes, depths (km), locations (Latitude and Longitude in degrees), radius of zone of influence (km ) and distances from Agra station (km). The radius of the zone of influence is calculated using the expression R = 100.43M, where M is the magnitude of the earthquake [21]. Although these earthquakes occurred far from the Agra observation station, at least two of them are well covered (>1000 km) by the radius of the zone of influence. Details of earthquake data are from the United States Geological Survey (USGS) website www.earthquake.usgs.gov.in. We also observed the variations of geomagnetic parameters such as Dst index and ∑ Kp index for each case separately and the data were taken from the National Aeronautics and Space Administration (NASA) website http://omniweb. gsfc.nasa.gov/form/dx1.html. We can see in Table 1 that all earthquakes have shallow depths except one (46 km), but we cannot ignore this earthquake because of its relatively large magnitude (M = 7.8). Furthermore, it is evident from Table 1 that two of the earthquakes occurred in the month of April, one in July, and the other two in September 2013. The top two panels of Figure 2 show the daily variation of GPS. -TEC for the month of April 2013 observed at Agra station. Here, the vertical TEC is represented by a dashed line and the corresponding sum (m + σ) and difference (m – σ) are represented by solid and dotted lines, respectively. On days when ... middle of paper ...... earthquakes occur, abnormal TEC variations cannot be attributed to these factors. The only reason for the anomalies are earthquakes, which are also supported by statistical analysis.IV. CONCLUSIONSIn this paper, we analyze three months' GPS-TEC data corresponding to five major earthquakes around the Indian subcontinent and statistical analysis is used for better interpretation of the results. The results of our study are as follows: We found TEC enhancements as precursors to major earthquakes around the Indian subcontinent, but these results contrast with the results of other researchers [4]-[6]. who also noted exhaustion. This contrast in results may be due to the latitude dependence and enhancements of the TEC data caused by the ascending electric field penetrating the ionosphere towards the east according to the mechanism mentioned above..