Abstract
<title>Abstract</title> <p>Siliguri Municipal Corporation, a Tier II city in northern West Bengal, faces severe seismic vulnerability from weak alluvial soil, dense development, and ageing buildings. The region falls under Zone VI in the revised IS 1893:2025 hazard map, placing it in the highest hazard category. This paper examines how social vulnerability and built environment vulnerability relate across the city. To trace root causes and the coupling between vulnerability components, a Social Vulnerability Index (SVI) was built for all 47 wards using census indicators. A Built Environment Vulnerability Index (BEVI) was developed for nine wards through field surveys, road mapping, and rapid visual screening that covered buildings, roads, layout, density, and open space. Social vulnerability varies across the city, with 9 wards in the high category. Among the nine wards with both indices, wards 4, 5, and 20 were high on social vulnerability, while 16, 22, 29, and 39 were low. The built environment shows different vulnerability. 57% of the 1,499 surveyed buildings face a high probability of Grade 3 damage, and 13% a very high probability of collapse. Only 55% of roads meet the emergency width standard, and 33% fall below it. Comparing the indices reveals compound vulnerability and mismatch. Wards 4 and 5 overlap strongly, while Ward 29 carries hidden physical vulnerability i.e., low social but medium built environment. The strongest link is between social disadvantage and post-earthquake road inaccessibility (Pearson r = 0.78). SVI can serve as a city-wide screening tool, while built environment assessment is needed for detailed diagnosis and planning.</p>