This study proposes a seismic hazard analysis method considering both affected area and spatial extent. Two indices, normalized affected area 𝛼 and spatial extent 𝜂, are introduced to characterize spatial damage patterns. A joint hazard framework is applied to evaluate the conditional distribution of 𝜂 given 𝛼 in a model region. Results show that 𝜂 effectively captures spatial variability of affected regions and that damage patterns differ even for the same affected area, particularly for smaller affected areas. The proposed method enables evaluation of diverse damage distributions. Future work includes incorporating exposure for risk-based assessment.
