17-01-2013, 10:07 AM
Assignment : Seismology
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Seismicity
Seismicity refers to the geographic & historical distribution of earthquakes.
The phenomenon of earthquakes is termed as seismicity
Earthquake activity in Pakistan is mainly concentrated in the north and western sections of the country, along the boundary of the Indian plate and the Iranian and Afghan micro-plates.
The Chaman Fault runs along Pakistan's western frontier with Afghanistan from Kalat, in the northern Makran range, past Quetta and then on to Kabul, Afghanistan.
The great 1945 Quetta earthquake was centered in this region.
This zone forms the boundary between the Arabian and the Iranian micro-plates.
Observatories
Seismic measurements started in 1954 when United States Geological Survey started installing World Wide Standard Seismographic Network (WWSSN) stations in Pakistan.
In1973 a nine station, seismic network, having a central recording system, was established by WAPDA with the help of Lamont Doherty Geological Observatory of Columbia University, USA, to monitor seismicity around Tarbela Dam.
Micro Seismic Study Program of Pakistan Atomic Energy Commission started playing an important role in the field of seismic monitoring from 1975 by establishing its seismic network for the site selection/evaluation of Nuclear Power Plants and other critical structures.
A seismic network of 30 stations was spread over 400x300 km area from north to south of Pakistan.