Bulletin of the Seismological Society of America; February 1997; v. 87; no. 1;
p. 265-271
© 1997 Seismological Society of America
On some microearthquakes near Tarbela reservoir during three low water stands
Kalpna and
R. Chander
Department of Earth Sciences University of Roorkee, Roorkee 247 667, India
Abstract
Detailed 3D stress analyses with a simulated model of Tarbela reservoir indicate that most nearby seismogenic faults inferred from observations of preimpoundment seismicity in the region should be stabilized even when the reservoir has low water levels during dry seasons. We hypothesize that the hypocenters of some microearthquakes occurring close to the reservoir during dry seasons of 1977, 1980, and 1981 were located on those of the above faults that are destabilized by accumulation of broadly north-south horizontal compressive stresses of plate tectonic origin. An order of magnitude analysis shows that the rate of accumulation of these stresses may be sufficiently rapid to overcome the stability imparted to the seismogenic faults by the Tarbela reservoir.
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