GUWAHATI, May 11 � Against the backdrop of a Parliamentary panel underscoring the urgent need for undertaking seismic microzonation studies of the major cities of the country, which are located in high seismic zones, the report of the seismic microzonation study of Guwahati is allegedly not made easily available for the common Guwahatians.
The report, result of a six-year-long study conducted since 2002, by a team of experts engaged by the Union Department of Science and Technology, at the request of Chief Minister Tarun Gogoi, was published about seven years back. It was released by the then Union Minister of Science and Technology Kapil Sibal at a function held at the Srimanta Sankaradeva Kalakshetra on January 18, 2008.
Releasing the report, Sibal had emphasised on the need of better awareness among the people of the NE region on seismic hazards, since the region falls in Seismic Zone -V, the highly vulnerable seismic zone.
The report was prepared by the experts of the Geological Survey of India, IIT Kharagpur, IIT Guwahati, IIT Roorkee, Assam Engineering College, Jorhat Engineering College, State Directorate of Geology and Mining, Central Ground Water Board, Regional Research Laboratory (RRL, now NERIST), Jorhat, India Meteorological Department and AMTRON.
In Chapter nine of the report, it is stated that the Greater Guwahati areas (the report described it as Guwahati Region) have been divided into four zones considering their respective earthquake hazard susceptibility point of view. They are � very high hazard zone, high hazard zone, moderate hazard zone, low and very low hazard zone.
For the purpose of arriving at this conclusion, the experts employed the historical 1897 Shillong earthquake of 8.7 magnitude �as the scenario earthquake.�
The very high zone, where the average shear wave velocity is 228m/s and the peak ground acceleration (PGA) level is very high and greater than 0.81g includes the western part of Guwahati region, which covers the areas of Bhattapara, Garal, Bulla, Singibari, Azara, Baharbari, Khanapara etc.
In the high hazard zone, the average shear wave velocity is 260m/s and the average PGA level is 0.52g. It covers the areas like Lachitpur, Teteliya, Mirzapur, Dekarpara etc. Guwahati Airport incidentally falls within the high hazard zone, said the report.
In the moderate hazard zone, the average shear wave velocity is 296 m/s and the average PGA level is 0.38g. The areas covered by this zone include � entire Bordang surface and its habitations like Dispur, Gopinath Nagar, Rehabari, Shantipur, Chatribari with important infrastructures like AMTRON, BSNL, Gauhati University and Irrigation Department located in it.
In the low and very low zone, the average shear wave velocity is 340m/s with a very low PGA level of 0.11g. These zones cover the areas near the eastern flank of the Brahmaputra, the areas in the periphery of the hills like Fatashil Hill, Kalapahar Hill and some areas in the eastern part of the region (Guwahati Region).
The report was prepared at a cost of Rs 5 crore by the Union Government.
According to the United States Geological Survey (USGS), the devastating April 25, 2015 earthquake rocked the areas near its epicentre in Nepal at a PGA level of 0.54g for three seconds and then with a PGA level of 0.46g for one second, followed by a PGA level of 0.08g for three seconds. This earthquake killed over 8,000 people as per the figures available till date.