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<p>Seismic Hazard Assessment (SHA) is critical for identifying areas prone to earthquake damage and informing disaster risk reduction strategies in urban regions. This study presents a first-level seismic hazard assessment for city-scale screening in Greater Chennai, a rapidly expanding coastal megacity in South India situated in Seismic Zone III. Given the absence of high-resolution borehole or geotechnical data, the analysis relies on open-access and reproducible datasets. Liquefaction susceptibility was evaluated using a GIS-based multi-criteria approach, where lithology, geomorphology, groundwater depth, and bedrock depth were ranked following established frameworks and weighted using a simplified Analytical Hierarchy Process (AHP). Peak Ground Acceleration (PGA) was estimated from published bedrock-level PGA values and adjusted to surface level using RADIUS-based soil amplification factors derived from lithological conditions. The weighted thematic layers were integrated in GIS through a weighted overlay to generate the final hazard map. Results indicate that about 24.67% of the region is classified within the high hazard category. Coastal and deltaic localities such as Adyar, Taramani, Sholinganallur, and parts of T. Nagar show relatively higher hazard due to recent alluvial and coastal deposits with shallow groundwater, and many of these areas also have aging infrastructure that could worsen earthquake impacts. The findings demonstrate a feasible approach for first-level seismic hazard assessment in data-limited urban environments and may support planners and decision-makers in identifying priority areas for detailed investigation and mitigation.</p>

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Integrated seismic hazard and liquefaction susceptibility mapping of a coastal megacity: a GIS-based first-level assessment

  • 期刊论文

  • 发表日期：

    2026年5月13日

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  • Saravana Ganesh Manoharan,
  • Ganapathy Pattukandan Ganapathy

摘要

Seismic Hazard Assessment (SHA) is critical for identifying areas prone to earthquake damage and informing disaster risk reduction strategies in urban regions. This study presents a first-level seismic hazard assessment for city-scale screening in Greater Chennai, a rapidly expanding coastal megacity in South India situated in Seismic Zone III. Given the absence of high-resolution borehole or geotechnical data, the analysis relies on open-access and reproducible datasets. Liquefaction susceptibility was evaluated using a GIS-based multi-criteria approach, where lithology, geomorphology, groundwater depth, and bedrock depth were ranked following established frameworks and weighted using a simplified Analytical Hierarchy Process (AHP). Peak Ground Acceleration (PGA) was estimated from published bedrock-level PGA values and adjusted to surface level using RADIUS-based soil amplification factors derived from lithological conditions. The weighted thematic layers were integrated in GIS through a weighted overlay to generate the final hazard map. Results indicate that about 24.67% of the region is classified within the high hazard category. Coastal and deltaic localities such as Adyar, Taramani, Sholinganallur, and parts of T. Nagar show relatively higher hazard due to recent alluvial and coastal deposits with shallow groundwater, and many of these areas also have aging infrastructure that could worsen earthquake impacts. The findings demonstrate a feasible approach for first-level seismic hazard assessment in data-limited urban environments and may support planners and decision-makers in identifying priority areas for detailed investigation and mitigation.