Seismic Risk Assessment of Built Environment in the Himalayan Foothill City of Dehradun, Uttarakhand

Himalayan foothill city of Dehradun in Uttarakhand state is located in a tectonically active region and is prone to earthquakes. The growth of Dehradun city is analysed using high resolution remote sensing datasets in the current study, with a focus on its vulnerability to seismic risks for single and double storey structures as the city is predominantly made up of low-rise structures. Analysis shows that 10% of urban expansion has occurred in spectral acceleration zones that are vulnerable to double-storey buildings, while 38% of urban expansion has happened in spectral acceleration zones that are vulnerable to single-storey buildings. The proposed land use as per Dehradun Masterplan 2041 is examined with reference to National Earthquake Hazards Reduction Program (NEHRP) for seismic regulating provisions. It is emphasized that the intended land use is incongruous in areas with higher spectral acceleration zones since it comprises structures with higher occupancy and the amenities required during post-earthquake rehabilitation. On the other hand, the open spaces are more appropriate in these locations, which will lessen susceptibility as the influence of seismic forces can be sufficiently attenuated. The present study, thus highlights the significance of including seismic risk information in urban planning processes in order to ensure resilient cities.