6. THE EARTHQUAKE RESISTANCE OF TAQ AND DHAJJI DEWARI FROM DAMPING AND POST- ELASTIC STRENGTH PERSPECTIVES
Soft, loose soils, such as those found in Srinagar and throughout the Vale of Kashmir, tend to amplify the longer-period ground motion characteristic of earthquakes with epicenters distant from the site. In many cases this effect can even make the earthquake last longer and may accentuate building damage. In the 2005 earthquake, with the soft soils, one would have expected the damage to the more flexible traditional taq and dhajji dewari buildings in Srinagar and Baramulla to have been more severe than it was, but this is where the energy dissipation inherent to both of these systems becomes a life-saver. The buildings are flexible but not very elastic. It is the damping from their inelastic behaviour that reduces their resonant response to the ground motion. Site response was a major problem in the 1985 Mexico City earthquake, in which the total collapse of numerous modern tall buildings caused many fatalities. The earthquake occurred 350 km (220 miles) from the city, but very soft soils beneath a 6 km square area in the city amplified the ground shaking, and many tall buildings including even one 21-storey building collapsed because they resonated with this long-period shaking, but lacked sufficient damping to decrease this resonance.