Reservoir Induced Seismicity in the Koyna–Warna Region, India: Overview of the Recent Results and Hypothesesстатья
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Дата последнего поиска статьи во внешних источниках: 21 августа 2017 г.
Аннотация:The state of the art in the geological and geophysical study of the region of Koyna and Warna water
reservoirs is reviewed. The probable geodynamical factors of induced seismicity are discussed. The detailed
geophysical surveys, satellite geodetic data, and time history of the seismicity in the region reveal a complicated
pattern of the structure and recent geodynamics of the region. The existing data suggest that the induced
seismicity is here most likely to be caused by the regional (intraplate) stresses driving the displacements along
the orthogonal network of the faults whose strength has dropped and continues decreasing due to the reservoir
impoundment and operation processes. The evolution of the seismicity which started immediately after
the rapid filling of the Koyna reservoir in the region of the dam, then rapidly expanded southwards and eventually
became concentrated in the region of the subsequently constructed Warna reservoir shows that seismic
events can be initiated by a number of factors whose contributions may vary with time. The key ones among
them include reservoir loading and its seasonal variations; water saturation of the faults which guide the propagation
of the front of fracture, increased permeability, and, probably, mineral transformations (hydrolysis)
under the water level fluctuations in the reservoirs; and displacement of the front of the high pore pressure
down to the main source zone of the earthquakes at a depth of 6–8 km. Based on the analysis presented in
the paper, we outline the directions of the future research aimed at studying the nature and dynamics of
induced seismicity in the region of large water reservoirs.