The Capital is broadly classified in two zones one half built on hard rock and the other on soft rock. While Connaught Place and the ridge area have been developed on hard rock, ITO, East Delhi and areas beyond the Najafgarh nullah are located on soft rock. It is the latter area, home to over one-third of the city's population, that is more vulnerable.

Settlements on soft rock, which include the entire Trans-Yamuna area, are likely to crumble faster when the rumblings start. The soft surface they are built on does not provide the required support structure for a multi-storeyed building. Geologist R K Verma says: ``Structures built in soft rock areas require strong foundations to withstandthe effects of an eqarthquake for a longer period. This will give people time to evacuate from the building. However, I don't think that builders keep an earthquake in mind during construction''.