SEISMIC SAFETY REGULATIONS IN WESTERN KENTUCKY: THE ROLE OF GEOLOGY IN PUBLIC POLICY
The Kentucky Geological Survey has been called upon by the Commonwealth to address the problems. The key finding by KGS is that geologists who conduct seismic hazard assessments have not made sufficient effort to communicate their products: what the maps are or what they mean. In particular, the seismic hazard maps have been incorrectly communicated. For example, the ground motion with 2 percent PE in 50 years is seismic risk by definition, but has been presented as seismic hazard. Even worse, the ground motion with 2 percent PE in 50 years has been presented as the ground motion that will occur in 2,500 years; it actually means there is about a 20 percent probability of that ground motion being exceeded if a large earthquake of about M7.7 occurs in 500 years in the New Madrid Seismic Zone. But because there is no historical or geological record to indicate the large earthquakes that could occur in 2,500 years in the New Madrid Seismic Zone, we do not know what ground motion could occur in 2,500 years, because ground motion is a consequence of earthquakes.
These miscommunications contribute to the difficulty in adopting and implementing policies for mitigating seismic hazard and risk in western Kentucky. Geologists should not only conduct seismic hazard and risk assessments, but also communicate their findings clearly to policy-makers and the public.