Large artificial water reservoirs in the vicinity of the Himalayan Foothills and reservoir-induced seismicity

There are 11 large reservoirs (exceeding a capacity of 1 km³ and/or the height of the dam being 100 m or more) in the vicinity of the Himalayan Foothills. Nine of these have been fully impounded. Only a couple of these reservoirs are adequately instrumented for seismic surveillance while the rest have inadequate instrumentation. However, there is no incidence of reservoir-induced seismicity reported from any of these nine sites. Nonoccurrence of induced earthquakes is comprehended primarily due to the thrust-fault environment, generally prevalent in the Himalayan Foothills, which is not conducive for reservoir-induced seismicity. Nevertheless, a few normal and strike-slip faults oblique and parallel to the general trend of the Himalayas have been reported where reservoir-induced seismicity could occur. All of these dams are located in a highly seismic area where earthquakes of magnitude exceeding 7 have occurred in their vicinity in the past. Normally occurring earthquakes, therefore, pose a much more severe threat to Himalayan reservoirs than do reservoir-induced seismicity.