Comment on nhess-2022-66

Abstract

The Indian landmass comprising of three broad morphotectonic provinces, namely the Himalaya and Tertiary mobile belts, Indo-Gangetic Foredeep and Peninsular shield have been jolted time and again by catastrophic earthquakes. The Socio-economic Risk Map of India generated by integrating vulnerable exposures with the IBC-compliant surface-consistent Probabilistic Seismic Hazard through an Analytic Hierarchy Process and expert judgement places the entire Himalayan stretch comprising of Kashmir Himalaya, Northwest India, Nepal together with Indo-Gangetic Foredeep, Bengal Basin, Darjeeling-Sikkim Himalaya, Northeast India and Bhutan in ‘High’ to ‘Severe’ Risk regime thus presenting this Tectonic Ensemble a typical case for site-specific study. Combined surface and downhole Geophysical and Geotechnical measurements classify this Tectonic Ensemble into site classes F/E, D4, D3, D2, D1, C4, C3, C2, C1, B and A with spectral site amplifications of 6.2, 4.8, 4.2, 3.9, 3.3, 2.58, 2.2, 1.87, 1.81, 1.4 and 1.2 respectively at 0.73–8.5 Hz frequency range thus facilitating surface-consistent probabilistic seismic hazard assessment in this Tectonic Ensemble exhibiting a PGA variation of 0.06 to 1.99 g whose structural impact is exhibited through SELENA-based building damage modelling using capacity spectrum method on the prevalent building types as ‘none’, ‘slight’, ‘moderate’, ‘extensive’ and ‘complete’ for all cities in the Ensemble.