Why is Probabilistic Seismic Hazard Analysis (PSHA) still used?

open3siAcknowledgements We thank Slava Gusiakov for calling the paper by Klemeš to our attention. We thank Peter Yanev and two anonymous referees for constructive comments. We thank David Yuen and Hou Yanping for their assistance and encouragement throughout the publication process. We thank Kei Hasegawa for assistance in drafting Fig. 1. This work was partially supported by a Grant (No. 16K05531) from the Japan Society for the Promotion of Science.Even though it has never been validated by objective testing, Probabilistic Seismic Hazard Analysis (PSHA) has been widely used for almost 50 years by governments and industry in applications with lives and property hanging in the balance, such as deciding safety criteria for nuclear power plants, making official national hazard maps, developing building code requirements, and determining earthquake insurance rates. PSHA rests on assumptions now known to conflict with earthquake physics; many damaging earthquakes, including the 1988 Spitak, Armenia, event and the 2011 Tohoku, Japan, event, have occurred in regions relatively rated low-risk by PSHA hazard maps. No extant method, including PSHA, produces reliable estimates of seismic hazard. Earthquake hazard mitigation should be recognized to be inherently political, involving a tradeoff between uncertain costs and uncertain risks. Earthquake scientists, engineers, and risk managers can make important contributions to the hard problem of allocating limited resources wisely, but government officials and stakeholders must take responsibility for the risks of accidents due to natural events that exceed the adopted safety criteria.openMulargia, Francesco; Stark, Philip B.; Geller, Robert JMulargia, Francesco; Stark, Philip B.; Geller, Robert