Identification of potential areas for the occurrence of strong earthquakes in Himalayan arc region |
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Authors: | S C Bhatia T R K Chetty M B Filimonov A I Gorshkov E Ya Rantsman M N Rao |
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Institution: | (1) National Geophysical Research Institute, Hyderabad, India;(2) International Institute of Theory of Earthquake Prediction and Mathematical Geophysics, Moscow, Russia;(3) Institute of Geography, Moscow, Russia |
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Abstract: | Morphostructural zoning (MSZ) scheme of the Himalayan arc region as obtained from a joint study of topographic, geological
and tectonic maps as well as satellite imagery is analysed. Three types of morphostructures have been determined: territorial
units (blocks of different ranks), linear zones limiting these blocks (lineaments) and intersections of the lineaments (knots).
Comparison of MSZ scheme with the know seismicity indicates epicenters of strong earthquakes (M≥6·5) clustered around some of these knots. Pattern recognition method is used to determine seismically potential areas for
the occurrence of recognition method is used to determine seismically potential, for the occurrence of strong earthquakes
of magnitude ≥M
0. We have carried out two such studies for the Himalayan arc region, one forM
0=6·5 and the other forM
0=7·0. Out of a total number of 97 knots, 48 knots are found to be seismically potential for the occurrence of earthquake ofM≥6·5. The results of the study forM
0=6·5 were presented in the symposium on “Earthquake Prediction” held in Strasbourg, France, March 1991 (Gorshkovet al 1991). The epicenter of Uttarkashi earthquake of magnitude,M
b=6·6 that occurred in the late hours of 19th October 1991 (UTC) lies in the vicinity of one such knot. The second study carried
out subsequently shows that only 36, knots are potential for the occurrence of earthquakes ofM≥7·0, which include the knot, associated with theUttarkashi earthquake. |
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Keywords: | Himalaya morphostructural zoning lineament knot pattern recognition earthquake potential |
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