With the death toll climbing to 3350 in Nepal, the April 25 earthquake is one the most devastating natural disasters to hit the subcontinent since the magnitude 7.6 earthquake quake of 2005 that killed at least 86,000 people and injured more than 69,000 and caused extensive damage in northern Pakistan.
Six hundred miles away, the people of Delhi were out on the streets several times over the weekend. The tremors being felt in the capital have raised the questions of the extent of Delhi’s vulnerability and level of preparedness in case it finds itself at the epicentre of an earthquake.
A category-IV seismic (certifying high risk) zone, several earthquakes of varying magnitude have hit Delhi since 1720, and at least five of them have been greater than magnitude 5.
Placed in the High Damage Risk Zone (MSK VIII)with regard to earthquake, Delhi’s vulnerability to large quakes is two-fold – one, arising out of its precarious perch atop several seismic fault lines (the Delhi-Hardwar Ridge, the Aravalli fault, Sonepat-Delhi-Sohna fault, the hidden Moradabad fault in the Indo-Gangetic basin and the junction of Aravalli and Sohna fault) and the other, due to its high density of population (it is the densest part of India with 11,050 per sq.km.!) . Add an absence of the law-abiding builders to adhere to seismic code provisions, and you have got the perfect recipe for disaster.
Settlement patterns, geological characteristics, such as depth of alluvial soil, also play a crucial role in determining the magnitude of risk.
These factors make the following areas most vulnerable to a tremblor – the trans-Yamuna area, extending till Noida and Faridabad . This part of town is vulnerable to damage even by a moderate earthquake because they lie on alluvial soil up to 200 m deep; alluvial soils amplify earthquakes.
Chhattarpur on the southwestern outskirts and the North Delhi ‘Ridge,’ which is right next to Delhi University’s North Campus, have also been identified as vulnerable areas, placing the nerve centre of Delhi’s university education at risk as well.
The Central Business District, better known as Connaught Place, numerous District Centres and the burgeoning high rise group housing schemes are high risk areas as well due to the vertical as well as plan configurations. The walled city area and scattered pockets of unplanned settlements also figure as high risk zones due to their substandard structures and high densities.
Delhi’s importance to the country, as a political, educational, industrial and commercial nerve centre of the country, cannot be overemphasised. A disaster in the country’s capital will have incalculable implications that will not just be limited to the capital region alone.
“There are buildings that are neither engineered nor adequately designed for an earthquake. Then there are those which are engineered but not adequately designed for earthquakes. In Delhi, 80% of buildings fall in either of these two categories,” Professor Mahesh Tandon, president of Indian Association of Structural Engineers, told the Times of India.
The last earthquake assessment exercise was carried out by the Delhi government four years ago in 2011. It was a fairly successful effort that saw a degree of disaster sensitisation, retrofitting of existing structures and so on, but several suggestions have yet to be implemented. Some of the pressing ones include the creation of a Tall Building Council like the one in Mumbai for high rise buildings, routine building audits, soil testing prior to approval of construction and a mechanism for monitoring adherence to the National Building Code (2005) and perhaps most importantly, updating the Seismic code to include flyovers, which have become ubiquitous in the city.
The Supreme Court had recently ordered all buildings that are occupied by 100 people or more should have a plaque to say what type of quake category it is. But these plaques are nowhere to be seen.
With such callous disregard for basic norms for quake-resistant buildings and assorted urban infrastructure, only prayers and divine intervention can save the Indian capital from an apocalypse in case of a major earthquake. The Nepal quake is a wake-up call!
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