Mangaluru prone to earthquakes, says survey

Mangaluru, May 6: According to an experts survey, it has been found that buildings in Bejai-Balmatta, Attavar -Hampankatta, have not adhered to IS 1893 : 2002, Part 1, which is the criteria for earthquake resistant design of structures, NITK?Civil Engineering Department Professor D Venkat Reddy said.

He was delivering a talk on ‘Earth, oceans and coastal zone management’, organised by Institution of Engineers (India) local centre an Institution of Valuers Mangalore Branch in Mangaluru.

The city falls in seismic zone-3 which means that the quakes of intensity six could occur. The buildings could withstand the earthquakes up to five in the Richter scale. As per Indian Standards on Earthquake Engineering, IS1893:1984 criteria for Earthquake Resistant Design of Structures, the country has been categorised into five seismic zones, based on the seismic intensity. IS is about earthquake resistant design of structures and is applicable to buildings, and other structures such as bridges, dams etc. Earthquakes of magnitude of eight take place in zone five. Nethravathi and Gurupur river basins are tectonically active.

As observed in Nepal, the structural failure of buildings have caused more amount of damage. In contrast, the Pashupathinath Temple is intact, though the building in its surrounding have been badly effected, which is due to the difference in structural pattern.

He further said that seismic waves alone are not responsible . Seismic activities take place round the clock. The earthquakes take place due to the sudden failure of strata. As per an estimation, around one thousand take place across the world everyday and three of them could be serious.

A lineament which is a fault in the underlying geological structure and the constructions on these lineaments such as railway tracks, bridges etc could cause more danger. IIS?has established a network system which records the seismic activities and which can even record 0.1 mm change in the crest of the earth. As per the movement of earth plates, a region will be displaced in a span of hundred years.