A bird’s eye view of the city. Picture by S.H. Patgiri

Dec. 22: With the city in the high–risk seismic zone, a “microzonation” map is under preparation to give the residents the precise data on their respective area’s vulnerability to earthquakes.

The map is also expected to become a “handbook” for builders, giving them the benchmark for specifications to be used in constructions, especially residential highrises.

The risk of disastrous aftermath of an earthquake in Guwahati — one of the 38 cities identified by the Centre as highly seismic and placed in the highest-risk zone — has increased in recent times with the boom in the construction of multi-storeyed buildings, many of which are not earthquake-resistant.

The Assam Electronics Development Corporation Limited (Amtron), the nodal agency for information technology (IT) for Assam is carrying out the project funded by the Department of Science and Technology (DST). The completion of the map will take another two years.

The other agencies collaborating in the project are the Indian Institute of Technology (IIT) in Roorkee, Kharagpur and Guwahati, the Indian meteorological department, Geological Survey of India, Assam Engineering College and National Geophysical Research Institute.

“The city will be divided into a number of zones to determine their vulnerability to earthquakes,” managing director of Amtron M.K. Yadava said. However, the map will not be able to predict the damage, which will be caused to man-made structures in the event of an earthquake.

Yadava said the microzonation map will be a basic tool for the planners to undertake development work as it will help in earmarking certain areas for specific activities.

He said the first-cut microzonation map, which will be able to give some details of the quake vulnerability, will be ready by May next year. “This will then be refined further to add more inputs for the final map,” he said. The final map will be ready by 2005, he said.

Amtron has set up its own Geographic Information System (GIS) centre for the project. Satellite images of the city have been procured for the map, Yadava said.

The agency officials said geological and geomorphological studies of the city are being taken into consideration for preparation of the map. Site response studies were undertaken at 300 points in the city using high-precision seismographs with motion and ground noise.

The Assam Engineering College is studying soil profiles. Land use map is being prepared with the help the environmental sciences department of the Gauhati University.

The Guwahati Metropolitan Development Authority (GMDA) is undertaking a rapid survey of all the highrise buildings in the city, which are susceptible to earthquake. A four-member committee headed by assistant professor of IIT Guwahati, H.K. Deb, has been constituted for the survey. The committee would fix a parameter on the basis of which the GMDA would identify the buildings that would require a thorough “engineering survey” to ascertain their vulnerability to earthquakes.

The GMDA is conducting the survey as per the instruction of the Centre, which has directed the state to take necessary precautionary measures for disaster management. The height of the buildings, conditions of the structure, breadth of the approach roads, availability of the open space will be the parameters for the rapid survey.

The city has also been included in the earthquake vulnerability reduction project of government of India and United Nations Development Programme’s (UNDP).

Altogether 13 of the 60 city Nagarik committees have been “activated” till now to prepare plans for earthquake disasters for their areas. “This will help develop ward-level earthquake response structures in order to reduce risks associated with this terrifying and destructive natural calamity,” an official said.