Some common and contrasting features of earthquake dynamics in major tectonic zones of Himalayas using nonlinear forecasting approach

Abstract

Although the Northeast, Western and Central Himalayas distinctly differ in their tectonic activities, this distinction is not examined from a dynamical perspective. The identification of dynamical pattern is, however, central for characterizing the appropriate models of seismic hazard analysis in such critical tectonic regions. We examine here the temporal evolution of seismicity (M ≥ 4) of the Central Himalaya (CH), Western Himalaya (WH) and Northeast Himalayas (NEH) for the period 1960-2003 using the modern nonlinear forecasting scheme to decipher the comparative determinism of underlying dynamical patterns, which may yield insight into earthquake processes. The nonlinear analyses of monthly resolution earthquake frequency time series suggest that earthquake processes in all three regions evolved on a high-dimensional chaotic plane, though with a contrasting predictive pattern. The predictive correlation analysis suggests that the available earthquake data of the NEH and WH can be predicted by more than 40-50%, whereas CH data only by 0-30%, implying that the earthquake dynamics in the NEH and WH are better 'organized' than in the CH. The significant distinction in the earthquake dynamical patterns seems to be associated with the underlying seismo-tectonics of these three regions. These results may place significant constraints for developing criteria to test the models of Himalayan earthquakes on a more rigorous and quantitative basis.