| Abstrakt: |
A significant amount of energy is released from sub-surface during an earthquake which is caused by seismotectonic activity. The occurrences of earthquake and its distribution pattern are necessary to correlate with concentrated and deviated energy in the sub-surface for better understanding the seismotectonic activity. Hence, the main aim of the present research is to develop hierarchical sub-surface energy anomaly index and its significant on seismotectonic activity by geospatial analysis of the seismic cluster zone and active tectonic signature through geoinformatics for Lower Tista sub-basin, India. In the present research, sub-surface energy has been quantified and threshold energy has been computed to estimate sub-surface energy anomaly in various hierarchical order. Also, the hierarchical sub-surface energy anomaly index has been computed and compared with the seismic cluster zone, seismotectonic activity, and geological formation. The analysis shows that the north and central part of the study region along Rathong chhu, Kalet Khola and Great rangit micro basin denotes as HSEAI Class V which represents low intensity earthquake with clustered concentration and includes in least to weak shaking anomaly zone. This zone is located in the fringe of greater and lesser Himalayan sequence along Main central thrust and inside Ramgarh thrust of lesser Himalayan sequence. It suggests higher energy concentrated and released through micro earthquakes along the active thrust with less energy anomaly. The southern part of the study region in quaternary surface adjacent to Himalayan foothills along Lish, Gish, Chel, and Dharala micro basin denotes as HSEAI Class II which are not resemble with any recent earthquakes and lies on least intensity sub-surface energy anomaly zone. This region intersects the frontal thrust and adjoins with Gish fault and Tista lineament which is presently not in active even though higher energy is concentrated in the sub surface. It suggests the energy anomaly is less even though energy accumulated in the sub-surface which signifies the energy concentrated in the sub-surface but not yet released. It predicts the energy may release with the displacement of thrust in future with higher magnitudes. [ABSTRACT FROM AUTHOR] |
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