Earthquakes contribute to approximately 20% of annual global losses from natural disasters, causing over 25,000 fatalities each year and significant socio-economic damage. Quantitative risk assessment has become a critical tool for mitigating and responding to earthquake-related risks. While South Korea experiences fewer and less severe earthquakes than its neighbors, recent magnitude 5 or greater events along the eastern coast have underscored the urgent need for region-specific risk assessments.This study introduces a deterministic methodology for evaluating seismic risks in three regions along South Korea’s east coast, identified as areas of potentially high seismic vulnerability. Unlike prior studies that often focus on macro-level analyses, this research employs a fine-scale 500-meter grid framework to integrate three key components: (1) historical earthquake occurrences, (2) population exposure, and (3) building vulnerability.Historical seismic data from 1978 to the present were interpolated to calculate cumulative magnitudes for each grid cell. Population exposure was quantified by aggregating data for individual buildings within the grid, providing a localized understanding of human vulnerability. Building vulnerability was assessed using the seismic fragility functions developed by South Korea’s Ministry of the Interior and Safety. These functions, incorporating variables such as structural type, seismic design status, site-specific ground motion, and amplification factors, were applied to estimate damage probabilities under a 2,400-year return period earthquake scenario. The damage rates for approximately 250,000 buildings were then converted into damage areas by applying them to the total floor area of each building.Key findings reveal significant spatial variations in risk across the study regions, with critical zones requiring immediate intervention. For example, highly vulnerable zones were identified near densely populated areas with older, non-seismically designed buildings. The results highlight the value of integrating grid-based frameworks, ground motion data, and fragility functions into seismic risk assessments, providing actionable insights for disaster mitigation and preparedness.This research advances the precision of regional seismic risk assessments and establishes a foundation for future developments, including probabilistic modeling and artificial intelligence applications. By offering tailored risk reduction strategies, the findings support policymakers and disaster managers in their efforts to reduce vulnerabilities and enhance resilience against seismic hazards.