| The  M6.9 earthquake hit Sikkim on 18th September 2011 at 6:11 PM IST  with its epicenter located at 27.72°N, 88.06°E, near Nepal-Sikkim  border, about  68 km NW of Gangtok and at a focal depth of 19.7 km. It was a shallow  focus  event, which was felt in India,  Nepal, Bhutan, Bangladesh  and Tibet.  Three aftershocks of magnitude 5.7, 5.1 and 4.6 were also felt in Sikkim  within 30  minutes of the earthquake. About 100 deaths are reported in India with the maximum of at least 60  in the  state of Sikkim.  The earthquake caused widespread damage and destruction in Sikkim  with the  maximum intensity of VIII at Chungthang and Lachung, VI in and around  Gangtok  and Mangan on MSK scale. Sikkim  lies in the second highest seismic zone (i.e., zone IV) of Indian  seismic code  IS: 1893 with the expected intensity of VIII in MSK scale. Non-existent  earthquake resistant construction led to unacceptable level of damage  to a  large number of RC buildings and some dramatic collapses even when the  intensity  of shaking was less than that expected in a design level earthquake  which  indicates their high seismic vulnerability. Consequently, the seismic  risk in  the region is growing at an alarming pace with increasing inventory of  seismically  deficient constructions. |  |