Comment on “Why earthquake hazard maps often fail and what to do about it” by S. Stein, R. Geller, and M. Liu

Abstract

Stein et al. (2012) contends that the occurrence of some recent destructive earthquakes in areas mapped as low hazard in some probabilistic seismic hazard maps “illustrates limitations of earthquake hazard mapping.” This statement is fundamentally incorrect. These instances illustrate that short-term observations such as recent seismicity do not characterize the hazard from faults with long recurrence-time earthquakes. This is not an inherent limitation in the methodology of probabilistic seismic hazard assessment (PSHA). They repeat arguments made in their previous articles, one of them recent (Stein et al., 2011) and others on the New Madrid region of the central United States that were published and commented on several years ago (e.g., Frankel, 2003, 2004; Stein et al., 2003). Stein et al. (2012) makes three major points: 1) the inputs to seismic hazard maps should include long-term geologic data in addition to historical and instrumental seismicity, 2) uncertainties in hazard values should be estimated and communicated to users, and 3) seismic hazard maps need to be objectively tested. The first two points have long been recognized and practiced in the seismic hazard mapping community in the United States and elsewhere. The third point has also been the subject of substantial work (e.g., Stirling and Petersen, 2006). This comment points out problems