Societal Perspectives about Earthquake Performance: The Fallacy of “Acceptable Risk”

Abstract

Seismic safety is a matter of public welfare involving potential loss of life or injury, disruption of communities, and costs to governments for addressing earthquake losses and recovery. Societal perspectives are incorporated into minimum seismic performance standards for codes and other guidelines. Discussion of revisions to these often entails consideration of acceptable levels of risk from a societal perspective. However, there is a fundamental Catch-22 in addressing acceptable levels of risk. On the one hand, determining these is fundamentally a value judgment that presumably requires some form of collective decision making. On the other hand, knowledge of relevant risk considerations, technical details, and costs and benefits are important for establishing meaningful standards. The first consideration argues for public processes for establishing safety goals. The second argues for deference to technical experts. Finding the appropriate middle ground is a serious challenge. I argue that a recasting of the discussion of acceptable risk is important for advancing seismic safety.