ABSTRACT
This chapter provides an overview of the earthquake precursory research scenario in India. The progression path of these activities is traced for two contrasting tectonic blocks, the Himalayan interplate region, where working models for earthquake occurrences are reasonably well established, and the Koyna–Warna zone, located in the stable shield region and known as a classic case of reservoir-triggered seismicity. The seismic swarm quiescence and nucleation trend have been used successfully to issue medium- and short-term forecasts, respectively, although they remain a case of singular success restricted to a single study area. The existence of short-term precursors to earthquakes in geophysical, geochemical and hydrological parameters is also abundantly documented, which broadly conforms to the hypothesized physical mechanism. In consideration of singular success stories, selective appearances and changing diagnostic signatures, no precursor or class of precursors can be considered deterministic for real-time short-term prediction, but they also cannot be rejected as chance detection. In the continued endeavour to improve the understanding of physical processes and prediction capabilities, two new initiatives include the establishment of Multi-Parameter Geophysical Observatories, making simultaneous measurements of multiple parameters, to enable their validation with each other and arrive at a synthetic probability for use in forecasting, and a major mission to drill a deep borehole and set up an observatory in Koyna to study the earthquake process in in situ conditions. The discussion ends with a brief account of the earthquake early warning program and the arrival time of destructive surface waves to urban cities prior to the earthquake’s arrival.
