Assessing the impact of foreshocks and aftershocks on the earthquake dynamics in northeast India using the non-linear forecasting techniques

Abstract

The modern concept of fractal and chaos theory has invariably been applied to earthquake time series to understand the nature of earthquake dynamics and hence to characterize the model behaviour. However, prior to proposing an earthquake generating model and predictive behavior of earthquake data, it is essential to understand the possible influence of foreshocks and aftershocks on the earthquake dynamics. We study the impact of foreshocks and aftershocks on the nature of earthquake dynamics using the modern nonlinear forecasting approach. We used here monthly frequency earthquake data sets obtained from one of the most seismo-tectonically crucial regions of northeast India bounded by latitude 20-28°N and longitude 88-98°E, spanning over a time window of 1920-1988. For the present purpose, two sets of monthly earthquake time series are prepared: (i) original earthquake data and (ii) data after removing foreshocks and aftershocks, and then analyzed separately using the non-linear forecasting approaches. Comparative results indicate that earthquake data free from aftershocks and foreshocks show better predictive behaviour than the original data (i.e. combined with aftershocks and foreshocks), thus revealing a significant effect of foreshocks and aftershocks on the model characterization of earthquake dynamics. © Geol. Soc. India.