Quake: IMD to complete microzonation of Delhi by April

[1]

In an effort that would help mitigate the hazards of an earthquake, seismologists will come out with a micro-analysis of the risks faced by different parts of Delhi in the eventuality of a major tremor by April.

The zone-wise risk assessment of the impact of a quake on Delhi, among 30 Indian cities in the severe intensity seismic zone, is on in full steam at the India Meteorological Department (IMD). Microzonation, as it is called, is carried out with the purpose of identifying separate individual areas that are found to have different potentials for hazardous earthquake effects.

The project, which is expected to be completed by April, would assess soil structure in various parts of the capital to give risk assessments on a zone-wise basis. Once completed, this will help in formulation of area-centric safety guidelines.

"Character of soil structure in Delhi is not uniform and with that varies the impact of an earthquake. To evaluate this, microzonation process at a map scale of 1:50,000 was done and a fresh process for further detailed microzonation in the 1:10,000 scale is on," R.S. Dattatrayam, a scientist with IMD's Seismic Department, told agencies.

This seismic microzonation would help seismologists categorise the soil type and structure of a particular region and assess the damage which might be caused to life or property in case of an earthquake.

Based on this microzonation data, the National Disaster Management Authority (NDMA) will be coming out with specific area-centric safety guidelines.

NDMA vice-chairperson Shashidhar Reddy said 240 engineers of Municipal Corporation of Delhi will also be trained to detect vulnerable structures in high-risk areas based on the new microzonation data.

According to the Seismic Zone Mapping done by the Geological Survey of India (GSI), Delhi is among 30 cities in the country falling in zone IV, which is defined as a severe intensity seismic zone.

An earthquake of 6 to 8 Richter scale magnitude in the Himalayas could trigger tremor shock in Delhi of up to 8 MMI (Modified Mercalli Intensity scale), Dattatreyam said.

On the Mercalli Intensity Scale, a similar earthquake in the Himalayas could result in slight damage in specially designed structures in Delhi and considerable damage in ordinary substantial building.

Focusing on the northern and central parts of India, which will have a direct effect on Delhi in terms of tremors and shock waves, basic microzonation of particularly vulnerable areas has also been conducted in Jabalpur and Dehradun.

Other than in Delhi, Dattatreyam said, the process of microzonation has begun for 30 other cities, including Mumbai, Ahmedabad, Siliguri, Vishakhapatnam, and Guwahati, as per standard guidelines set for this exercise.

This year, till February 16, there were 15 earthquakes in India, the latest being recorded at 5.0 on the Richter scale off the West Coast of Great Nicobar Islands--the most pro-active seismic region in the country.

According to IMD, there were 80 earthquakes in India in 2011, which measured between 3.5 to 6.5 on the Richter scale.

A majority of these quakes occurred in the northern Indian regions of Jammu and Kashmir, Harayana and Punjab.