Seismic hazard analysis and risk classification for major dams in Thailand: a nationwide study

Abstract

Abstract Background Seismic hazards pose increasing challenges to the safety of large dams in Thailand, particularly those located near active fault systems. Despite the critical role of dams in water resources, hydropower generation, and flood control, a comprehensive nationwide seismic hazard assessment has not previously been conducted. Methods This study evaluates the seismic hazard of 39 major dams across Thailand using quality-controlled earthquake records spanning 1964–2015 and active-fault data. Deterministic Seismic Hazard Analysis (DSHA) and Probabilistic Seismic Hazard Analysis (PSHA) were applied to estimate Peak Ground Acceleration (PGA), Maximum Credible Earthquake (MCE), and recurrence-based design parameters, including Operating Basis Earthquake (OBE), Design Basis Earthquake (DBE), and Maximum Design Earthquake (MDE), following ICOLD recommendations. Gutenberg–Richter parameters were also calculated to characterize regional seismicity. Results The MCE values associated with the nearest recognized faults range from 6.7 to 7.9 M w , while the recalculated 84th-percentile deterministic PGA values range from 0.023 to 0.503 g. Relatively high calculated seismic hazards are concentrated mainly in northern and western Thailand, reflecting the influence of major active fault systems and shorter source-to-site distances. Nine dams—Mae Ngat Somboon Chon, Mae Kuang Udom Thara, Kiew Kho Ma, Kiew Lom, Sirikit, Vajiralongkorn, Srinagarind, Tha Thung Na, and Rajjaprabha—are classified as Class 4 under the author-developed screening framework, based on DSHA PGA values exceeding 0.25 g and distances of 10 km or less from the nearest recognized seismogenic fault. Lower calculated hazard levels occur at many of the remaining dam sites. Conclusion The integrated DSHA–PSHA framework provides a consistent basis for nationwide seismic hazard evaluation and comparative hazard classification of dams. The results identify dam sites with relatively high calculated seismic hazard and can support prioritization for further site-specific assessment and monitoring in Thailand.