When the ground beneath shook
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Natural calamities like earthquakes occur without warning, but seismic experts feel that lives can be saved if vulnerable areas are demarcated since it would be as good as predicting the disaster.
The state and central governments are sitting on an old report prepared by the Indian Institute of Science (IISc) on ‘Seismic Microzonation of Bangalore Urban Centre’ which clearly highlighted the vulnerable parts of the city and surrounding areas in the event of an earthquake. According to the report, the city has three potential seismogenic sources - Arkavathi Fault, Mandya–Channapatna–Bengaluru zone and Chelur, Kolar and Battipalle. Of these three, researchers are now emphasizing on a macro-level study on Lineament 15 that runs across the city.
The report aims to provide a clear planning pattern for Bengaluru as far as building construction is concerned and give ideas to urban planners and civil contractors on where to build tall buildings. The report is a comprehensive research of seven years by the team of experts from the Department of Civil Engineering, led by Prof T.G. Sitharam.
The IISc established an earthquake monitoring centre (Broad Band Centre) on its campus and, in the last two years, several quakes reported in other parts of the world are being recorded here. “The idea is to monitor the seismic zones around Bengaluru in a radius of 300 km since the ripple effects of any earthquakes are felt in areas situated as far as 250-300 km from the epicentre. What we saw in Indonesia was of higher magnitude and the effects were felt in Indian cities. We have got some minor readings after the tremors in city on Wednesday which will be calculated in the next few days,” Professor Sitaram said.
The seismic experts also contend that the earthquake hazard can amplify by 2-3 times for structures that are built on tank beds. And there are number of structures have been built where water bodies previously existed. “When you know that the city is under the seismic zone and more amount of studies are required to pinpoint the danger zones of Bengaluru, the city planners must avoid high-rises from being built in such areas. But, if you look around, most of the high-rises are built on lake beds. Besides the areas which fall in the Lineament and seismic zones, buildings on lake beds are vulnerable during natural disasters,” warns Dr T.V. Ramachandra of IISc.
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