Experts favour quake-resistant constructions in Uttarakhand, HP

Sandeep Rawat

Tribune News Service

Haridwar, April 29

To assess the impact and cause of the recent earthquake in Nepal, a team of experts from IIT-Roorkee will visit the affected areas and asses various aspects, Dr ML Sharma, Head of Department Earthquake Engineering, IIT-Roorkee, has said.

Sharma said this inspection will help know the exact reason for the earthquake, damage done, condition of buildings, houses and measures to be adhered to so as to minimise the loss in future. Structural dynamics, soil dynamics, engineering seismology, seismotectonics and instrumentation would be documented during this visit.

Dr Sharma said the seismic zone is ultra sensitive from Nepal till Kangra in Himachal Pradesh.

Citing data, he said that in 1934, a 8.4-scale earthquake was recorded in Nepal, though in the past few decades no major high magnitude earthquake had been felt in this seismic zone.

This, he pointed out, had also resulted in the generation of a certain pressure or strong ground motion, which resulted in the April 25 earthquake. It was an indication of a similar one likely to occur in future.

“The earthquake’s centre was at Kodari in Nepal, which was measured on the Richter scale at 7.8. In India, at 4.45 am, a 5.6-magnitude shiver was recorded, with the highest being 6.9 at 12.39 hours. In the evening at 18.41 hours, a 4.1 recurring earthquake was recorded. On Monday, at 12.44 hours for 20 seconds a mild earthquake was felt,” said Dr Sharma

Dr Sharma has done a study on shallow earthquakes in the Indian region and seismological research around the Tehri dam region.

Experts at the IIT say that the earthquake was triggered by the India tectonic plate, which is moving northwards at the rate of 5 cm a year into Central Asia. This results in thrust-faulting and has thrown up the Himalayan mountain range. In the previous and early part of this century, it has triggered several other significant earthquakes in this region.

These include the 1934 earth quake in Bihar, which was recorded at a magnitude of 8.2. While at Kangra, Himachal Pradesh, it was recorded at 7.5, the event in 1905 and in the 2005 Kashmir earthquake, the Richter measured it at 7.6

Citing lack of earthquake-resistant techniques in constructing houses and buildings, Prof Yogendra Singh of the Earthquake Engineering Department suggested the usage of latest technology to ensure lessening of damage to human life and property.

Professor Singh said even the already constructed buildings can be modified to ensure that the impact of earthquake is minimum.

“Focus should be given on horizontal portion of the buildings too, which sustain major pressure of the whole building and sustain earthquake impact to a larger extent. Earthquake-resistant design and scientific inputs should be taken into account or made mandatory while allowing the construction or passing of maps of all buildings. Prevalent construction practices and building typology result in dwelling units that are extremely vulnerable to earthquake hazards. Earthquake-resistant design and detailing should be made mandatory under normal design situations,” he suggested.

Professor Singh added that contrary to normal perception that usage of quake-resistant technology is costly, this technology only ups the total cost of building by as much as 5-7 per cent in newer ones, while in older ones, just 10-15 per cent cost of the total building is sufficient to make them quake resistant.