KOLKATA, Jan 4 - The earthquake that devastated Manipur on Monday and rocked other Northeastern States, as well as neighbouring Myanmar, Bhutan and Bangladesh, is not connected to last year�s April 25 Nepal earthquake, experts have asserted, saying the impetus should be on adhering to building codes for earthquake-resilient structures.
The April 25 killer quake in the Himalayan nation, measuring 7.9 on the Richter Scale, had claimed over 8,000 lives. However, seismologists and geologists have quashed rumours of the Manipur earthquake being an after-effect of the Nepal temblor.
�It is not connected to the Nepal earthquake,� clarified R Dharuman of Geological Survey of India (GSI), adding a GSI team will be sent out to map the region and launch studies on the temblor. Manipur is situated in seismic zone V, the most earthquake prone in the country.
The temblor occurred as the result of a strike-slip faulting (vertical or nearly vertical fractures where the blocks have mostly moved horizontally) in the boundary region between India and the Eurasian plate in southeast Asia, according to the USGS. Allaying fears, BK Rastogi, former director general of Gandhinagar-based Institute of Seismological Research (ISR) said this earthquake is �not an indicator precursor to a larger earthquake� in the near future.
�However, monitoring is essential. The (Indo-Myanmar) region is full of faults and many active faults are there. Monitoring and enforcement is totally missing in India. The government has to ensure monitoring and enforcement of rules while adherence to building codes must be maintained to minimise losses,� Rastogi said.
India�s Northeast region is considered the world�s sixth most earthquake-prone belt.
The region has a history of powerful earthquakes caused by the northward collision of the Indian and Eurasian plates. They are moving towards each other at a rate of 4-5 cm per year. Data from Manipur�s National Institute of Disaster Management shows that earthquakes of low to moderate intensity are regularly recorded in the State.
The State has weathered dozens of large earthquakes, the biggest in recent times being the 1988 temblor measuring 7.2 on the Richter Scale. The distinguishing feature of Monday�s quake is its duration, pointed out IIT Guwahati�s Chandan Mahanta. Factoring in the vulnerabilities, site-specific building codes must be followed, Mahanta iterated.
�The thing that causes damage is the material on which the buildings are standing. Generally, the soil magnifies the seismic waves more so there will be more acceleration and on rocks it is sometimes less.
�In Manipur, there are some areas where there must be soil and rocks in others. The impact also depends on the number of storeys of the building. Short buildings are vulnerable in rocky foundations and tall buildings are fine on rocky foundations. Similarly, tall buildings are vulnerable in soil foundations,� added Mahanta. � IANS