The Geological Survey of India is busy preparing seismic hazard microzonation maps of Vijayawada to prevent loss to life and property in case an earthquake hits the city. Vijayawada is the only major place in Andhra Pradesh that falls under the “Earthquake zone III.” The rest of the state falls under the “Seismic zone II,” which is relatively safer. Once the microzonation maps are ready, the Earthquake Geology Division of the GSI will advise the municipal corporation about the areas in the city that are vulnerable to earthquakes, particularly high-rise buildings. The Vijayawada urban agglomeration has a population of over 17 lakhs and as many as 22 seismic sources, mainly faults, in and around the city have been identified. The Gundlakamma fault is the most active fault in the vicinity.

The city has four types of soil with black cotton soils making up 58 per cent; sandy clay loams 23 per cent, red loamy soils 17 per cent and sandy soils 2 per cent. The microzonation maps will be prepared on a scale of 1:10,000 to 5,000 and will be useful for disaster management. Similar studies have been proposed for other seismic areas like Ongole and Bhadrachalam too.

As part of the seismic microzonation, the city has been divided into sub- regions in which different safeguards must be utilised to reduce, and prevent damage, loss of life and societal disruptions during earthquakes. The maps will also help mitigate the effects of an earthquake by quickly determining source parameters and acquiring information about the local geology and soil profile, topography, depth of the water table, characteristics of strong ground motions and their interaction with man-made structures.

According to senior geologist, Prof S.K. Nath, earthquake disasters are inevitable but it is possible to minimise the damage caused by an earthquake if the zones that are more susceptible to undergo maximum ground motion are identified. Seismic microzonation helps by providing a realistic picture in terms of ground motion at a higher resolution. Based on the earthquake maps, the city civic body may come out with specific designs for buildings and structures, assess seismic risk to the existing structures, and provide guidelines for management of land use.