Adaptive techniques for extraction of pre-seismic parameters of Total Electron Content (TEC) at anomaly crest station

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 (TECpeak.). The use of a single parameter such as TECpeak 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 (26 degrees 10' N, 91 degrees 45' E), an equatorial anomaly crest station.