An assessment of geomorphometric anomalies and their significance on the seismotectonic activity through geoinformatics

Abstract

The natural system of the drainage basin is interrupted by sub-surface faults and active tectonic processes. The anomalous nature of the drainage network and its basic morphological characteristics produce significant geomorphometric anomalies of the drainage basins which are an indicator of seismotectonic activity. In recent years, the increasing frequency of earthquakes and the subsequent damage in the Indian sub-continent necessitates a study of the seismotectonic significance with special reference to morphometric analysis. Hence, the present research is focused on studying the geomorphometric anomalies at a micro basin level and their impact on seismotectonic activity using geoinformatics. The study area is the lower Tista sub-basin which belongs to the Himalayan mountain in the northern part, whereas the southern part represents a peneplain surface. The quantitative databases of various morphometric parameters have been generated using digital elevation model data and satellite images to identify the geomorphic anomalies at the micro basin level which have been compared with past seismological databases to understand the impact on seismotectonic activity. The result shows that the drainage bifurcation, anomalous drainage network, drainage compression along the mountain front, narrow steep valleys in the high resistance surface, neotectonic deformation and the asymmetric valley shape are probable geomorphometric anomalies which coincide with past seismic activity in the study region. The present study also shows that the tectonic tilt, compressed meanders in the uplifted surface and the linear valley in the alluvial surface are also equivalently significant for past earthquake occurrences in the foothill zone. It is also observed that the elongated and linear micro basins and the presence of a strike–slip fault with major lineaments in the Quaternary surface are great indicators of geomorphometric anomalies which have no resemblance with any significant earthquake in the past and are equally important signatures of seismotectonic activity. The study concludes that the geomorphometric anomaly is an important parameter of seismotectonic activity which can be used for studying seismic hazards in the future.