Delhi: Safe from Earthquakes?

earth1.jpgThe early morning of 26 November was a terrible alarm for me and I woke up three hours before my normal weekday waking up time. I was shaken awake from a deep sleep and I realized that everything around me was moving, even the windows were banging on my head. The actual realization hit me only seconds later and I just ran out from my house. It became the talk of the day for the Delhi-ites; this matter was heard everywhere in my college also. When I was talking with my friends about this same issue, I discovered that

Delhi was quite prone to earthquakes. This was enough for me to start a research and get to know if

Delhi really is prone to quakes.

Delhi region has a long seismic history, it being affected by earthquakes of local origin as well as those of Himalayan origin. Based on the tectonic map of the region prepared, the area is characterized by several dominant features such as the Delhi – Haridwar ridge, the Aravalli – Delhi fold, the Sohna fault, the Mathura fault and the

Moradabad fault. The distribution of the epicenters appears to have a NE-SW trend, correlated with the direction of major tectonic features of the region. Coupled with the settlement pattern, the geological characteristics, such as depth of alluvial soil, play a crucial role in determining the magnitude of risk. For example, the

Narain-Patel Road

section and the Yamuna River bed section extending till Noida and

Faridabad are more vulnerable to damage even by a moderate earthquake because they are on alluvial soil up to 200 m deep. These regions face a very grave problem of soil liquefaction during an earthquake. Moreover, earthquakes are amplified by the alluvial soils. The Ridge is comparatively safer as it has a rocky base.

Delhi has some heavily populated colonies on deep deposits of alluvium in various locations, particularly in the trans-Yamuna area. These areas are seismically vulnerable as large ground motion amplifications are expected due to their typical ground compositions.In the past, since 1720 AD, five earthquakes of Richer Magnitude of 5.5 to 6.7 are known to have occurred in the UT of Delhi or close to it. Two major lineaments, namely the Delhi-Haridwar ridge and Delhi-Moradabad faults, pass through the territory, both having a horrible potential of generating earthquakes of magnitude upto 7.0 on the Richter scale. Normal depth of 30 km may be assumed for these earthquakes. It will be prudent to consider the effects of such a potential earthquake for developing a prevention-cum-preparedness plan. However according to one of Times of India article in edition of 2001 which was published shortly after Bhuj (

Gujarat) high intensity earthquake,

Delhiā€™s seventy percent buildings can collapse due to a high intensity earthquake. As per the article, as the buildings are getting constructed in larger numbers, the quality is being neglected and the architects are failing to keep in mind that

Delhi is prone to quakes. Those pockets with high rise buildings or ill-designed, high-risk houses exist without any specific consideration about being earthquake resistant. Similarly, unplanned settlements with substandard structures are also prone to heavy damage even due to a moderate shake. Hence it is very vital and absolutely necessary that Building Planning, keeping in mind the threat of a major earthquake, should be the major concern for the Delhi-ites or else it will all be reduced to dust.

Anu Prakash