Site Characterization vis-à-vis Probabilistic Seismic Hazard and Disaster Potential Modelling in the Himalayan and Sub-Himalayan Tectonic Ensemble from Kashmir Himalaya to Northeast India at the backdrop of the updated Seismic Hazard of the Indian Subcontinent

Abstract

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.

A non-extensive approach to probabilistic seismic hazard analysis

“…The main objective of PSHA computations is to calculate ground motions with different exceedance probabilities during a specific time interval (Anbazhagan, 2019). This information is the gateway to defining the possible scenario earthquakes and is used to develop instructions for seismic codes and standard regulations (Nath, 2022;Iervolino, 2022).…”

Simulation of a plausible great earthquake (Mw 8.0) sourced on down-going Indian slab beneath Indo-Burmese wedge and its implications for North East (NE) Indian region

“…Also, the intermediate depth of the earthquake led the seismic waves originated from the upper mantle and travelled with less attenuation in the medium to reach up to SHL station and hence resulted in the maximum PGA at a hard rock site(Gahalaut et al 2016). Various research works on Probabilistic Seismic Hazard Assessment (PSHA) and Deterministic Seismic Hazard Assessment (DHSA) have been carried out in these seismically active tectonic reigme of NE Indian region(Mohan et al, 2008;Sharma and Mishra, 2020;Nath et al, 2022) Khattri et al (1984). andBhatia et al (1999) have computed PGA values of 0.8 g (785 cm/s 2 ) and 0.45 g (441 cm/s 2 ) respectively for 10% probability of exceedance in 50 years during PSHA Parvez et al (2003).…”