A Framework for Assessing Seismic Hazard Risks in Urban Geology

Thesis Abstract

Urban areas worldwide are increasingly vulnerable to seismic hazards due to rapid urbanization, inadequate underlying geological assessments, and the variability of seismic risk across diverse urban settings. This study addresses the critical need for a systematic, comprehensive framework to assess and quantify seismic hazard risks within complex urban geological settings, aiming to enhance risk mitigation strategies and inform urban planning policies. The primary objectives are to develop an integrative seismic hazard assessment model tailored to urban geology, evaluate the influence of local geological and infrastructural factors on seismic risk levels, and establish spatial risk maps that can be utilized by policymakers and urban planners. The research adopts a mixed-methods approach, combining quantitative geotechnical and seismic data analysis with qualitative stakeholder interviews. The study population comprises geotechnical surveys from twenty-five key urban districts within the metropolitan corridor of the city, each characterized by distinct geological formations and infrastructural densities. A sample of 150 geotechnical borehole data points is systematically selected through stratified random sampling to ensure geological representation. Data collection involves the compilation of seismic hazard parameters—such as peak ground acceleration (PGA), site amplification factors, and soil liquefaction potential—obtained from regional seismic monitoring agencies and site-specific geotechnical investigations. Additionally, structured questionnaires and semi-structured interviews are administered to fifty urban planners, civil engineers, and emergency management practitioners to capture contextual and infrastructural risk factors. Analytical procedures employ Geographic Information System (GIS) spatial analysis tools to integrate geological, seismic, and infrastructural data, complemented by advanced statistical techniques including multiple regression analysis to quantify the influence of geological variables on seismic amplification, and factor analysis to identify the most significant risk determinants. The framework incorporates established theories such as the Site Response Theory and the Seismic Risk Paradigm, alongside a newly formulated Urban Seismic Risk Assessment Model (USRAM) that synthesizes geotechnical and infrastructural parameters into a unified risk index. The model’s validity is tested through cross-validation with historical seismic damage records and sensitivity analysis. It is anticipated that findings will reveal critical correlations between local geological features—such as soil type, layering, and groundwater presence—and variations in seismic risk levels within the urban mosaic. The derived spatial risk maps are expected to identify high-risk zones, thereby enabling targeted mitigation efforts and informed land-use planning. The study will contribute to existing knowledge by advancing a holistic, adaptable framework that integrates geological, infrastructural, and community resilience factors into seismic hazard assessments, filling significant gaps in localized seismic risk modeling. The research concludes that effective seismic risk management in urban areas necessitates an interdisciplinary, data-driven approach exemplified by the developed framework. Recommendations include the institutionalization of the USRAM into urban planning policies, routine geotechnical surveys for critical infrastructure, and capacity-building initiatives for stakeholders on seismic risk mitigation. Furthermore, the study advocates for ongoing data acquisition and model refinement to adapt to evolving urban landscapes and climate-induced geological changes, thereby supporting resilient urban development in seismic-prone regions.