Total electron content (TEC) data, obtained from satellites, are used in the search for imprints for identifying the probability factor of an impending earthquake. Extraction of earthquake induced signature is done mainly from day-to-day variations in TEC peak (TEC peak. ). The use of a single parameter such as TEC peak is not always enough to formulate such a pointer. The paper therefore focuses on the need to introduce other markers such as the shape of TEC profile and to utilize any modification in the profile shape caused by an impending earthquake to identify precursors. An automatic pattern matching approach for processing global positioning system (GPS) generated TEC records is introduced to achieve this aim and TEC profiles are passed through a template framed from the time series of quiet day data. The Dynamic Time Warping (DTW) algorithm is adopted to look for deviations in the entire TEC profile of days prior to the earthquake with respect to the template. Variation, if any, would be used as an index of earthquake induced signature. A few case studies using this algorithm are presented in the paper. Work is based on TEC data collected from the GPS receiver at Guwahati (268 10 0 N, 918 45 0 E), an equatorial anomaly crest station.

The processes leading to the growth and inhibition of equatorial anomaly before major earthquake (EQ) were viewed in this paper by examining global Total Electron Content (TEC) that contoured over longitude sectors covering Africa to Pacific, in association with EQ events of Japan (M = 9) that occurred at 135°E to 145°E and 35°N to 40°N, on March 9 and 11, 2011 and of Indonesia (M = 8.6) that took place at 2.311°N, 93°E, in April 11, 2012. The paper focuses on the development of abnormal increase in density in the night sector around—10° latitude zone prior to the two major EQ events, though their epicenters are separated widely from the anomaly region. The F-layer density variations from relevant locations and TEC features obtained from GPS at Appleton anomaly crest station are utilized as supporting inputs. The possible sources leading to the anomalous development in density are discussed in the frame of EQ time consequences of lithospheric-atmospheric processes between the equator and beyond. The role of electric field generated by pre EQ preparatory activities and dynamical coupling modes through seismic fault line are brought in to the ambit of discussion.