31-24 InSAR Data-Driven Building Damage Risk Assessment for Coastal South Asian Cities using BRASE Framework

Session: Environmental Geochemistry and Health (Posters)

Poster Booth No.: 50

Presenting Author:

Ibrahim Isiaka

Authors:

Isiaka, Ibrahim Opeyemi¹, Sadhasivam, Nitheshnirmal Opeyemi², Khorrami, Mohammad polytechnic institute and state³, Wise, Clayton Opeyemi⁴, Shirzaei, Manoochehr Opeyemi⁵

(1) Geosciences Department, Virginia Tech, Blacksburg, VA, USA, (2) Geosciences Department, Virginia Tech, BLACKBURG, VIRGINIA, USA, (3) Geosciences Department, Virginia Tech, BLACKBURG, VIRGINIA, Nigeria, (4) Geography Department, Virginia Tech, BLACKBURG, VIRGINIA, USA, (5) Geosciences Department, Virginia Tech, BLACKBURG, VIRGINIA, USA,

Abstract:

Land subsidence represents a persistent yet undercharacterized hazard across part of South Asian coastal cities, where rapid urbanization, groundwater extraction, and sedimentary geology collectively drive land sinking. This study presents a multi-city assessment of vertical land motion (VLM) and building-scale subsidence risk across 14 South Asian coastal cities using Sentinel-1. InSAR-derived deformation estimates integrated within BRASE, a novel open-source building risk framework synthesizing hazard, vulnerability, and exposure across approximately 6.3 million building footprints. Mean subsidence rates range from -1.4 mm/yr in Visakhapatnam to -10.6 mm/yr in Chittagong, with temporally accelerating deformation identified in Chittagong, Karachi, Mumbai, Kochi, Visakhapatnam, and Thiruvananthapuram. Mean distortion angle thresholds indicative of building failure have in most areas within each city yet to exceed the 1/500 threshold. However, population exposure analysis reveals that tens of thousands of residents across Karachi, Chittagong, Mumbai, and Chennai occupy high- or very high-risk buildings, with risk burdens possibly falling disproportionately on economically vulnerable populations and smaller urban centers. Non-residential buildings exhibit systematically disproportionate fractional risk exposure, highlighting threats to economic stability. These findings provide an evidence base for integrating subsidence risk into disaster risk reduction, groundwater governance, and urban planning across South Asia.

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.