Site effect assessment and vulnerability analysis using multi-geophysical methods for Kangra city, NW Himalaya, India

Even after a century, the site-specific seismic parameters are unidentified for seismically vulnerable Kangra city, which has witnessed a disastrous effect from the 4th April 1905 Kangra earthquake ( M s 7.8). This earthquake resulted in a varied damage distribution from the unconsolidated Quaternary sediments (alluvial fans to boulders conglomerates). The site-specific response analysis was carried out with multi-geophysical approach. The seismic methods, viz ., ambient noise measurement and multichannel analysis of surface waves (MASW), were employed to understand local site conditions. horizontal to vertical spectral ratio (HVSR) peaks and their corresponding frequencies are interpreted for subsurface characterization. The fundamental frequency ranged from 4.23 to >20 Hz and the amplification factor varied from 1.5 to 6.67. The vulnerability analysis was carried out to identify the weak zone on the surface. The HVSR analysis shows that dominance of high fundamental frequency ( f 0 > 10 Hz) component also brings possibility of heavy damage from a near-source earthquake. While the results from MASW provide two-dimensional (2D) shear wave velocity ( V s ), which are used for comparison and validation. These results provide important input for earthquake-resilient planning with resilient structures as per local site conditions. Research highlights Multi-geophysical seismic methods were tested in the complex geologically sedimentary environment of Kangra city, NW Himalaya, India. Estimation of predominant frequency and amplification from ambient noise records. Active seismic data acquisition of Multichannel Analysis of Surface Waves (MASW) for comparison and validation. Evaluation of site-specific characteristics for vulnerability analysis and earthquake risk management.