Why Earthquake Research Matters

Earthquakes have occurred in and around Kentucky in the past and continue to occur (Fig. 1). The strongest historic earthquake recorded inside Kentucky's borders was the magnitude 5.2 Sharpsburg earthquake of July 27, 1980, in Bath County. The quake caused an estimated $3 million in damage in Maysville (Fig. 2). The 2012 Perry County earthquake (magnitude 4.2) caused minor damage to the Letcher County Courthouse in southeastern Kentucky. The most significant earthquakes to have affected Kentucky occurred from December 1811 to February 1812 in the New Madrid Seismic Zone. At least three large earthquakes, each estimated to have been greater than magnitude 7, occurred during that period. Though the state was sparsely settled then, these earthquakes affected the whole commonwealth. The New Madrid Seismic Zone is the most active seismic zone in the central and eastern United States, and a repeat of earthquakes with the same magnitude as the 1811-12 earthquakes could cause significant damage in Kentucky. Thus, earthquakes have an impact on the commonwealth.

Figure 1. Earthquakes with magnitude greater than 3, indicated by red dots, and seismic zones (shaded areas) in and around Kentucky.
Figure 2. Damage to a home caused by the Sharpsburg earthquake of July 27, 1980.

Although predicting earthquakes is impossible, the potential damage they cause can be mitigated through earthquake-resistant measures, such as codes for buildings, homes, and infrastructure. The Kentucky Building and Residential Codes (Fig. 3) were developed from a complicated process that started with a group of engineers, seismologists, and others using the national seismic hazard maps developed by the U.S. Geological Survey and engineering science. The codes developed a set of recommendations, including design ground motions, for seismic regulations for new buildings and other structures. These recommendations were endorsed by the Federal Emergency Management Agency and thus became federal policy, along with associated regulations for seismic safety. The recommendations were then adopted by state government agencies, as well as nongovernmental organizations such as the International Building Code Council.

Figure 3. Development of the Kentucky building and residential codes.

As shown in Figure 3, the national seismic hazard maps were based on scientific information applicable to the entire country. The scientific information used for these maps may not reflect the unique geology of Kentucky, however. In other words, the national seismic hazard maps are not optimal for the development of building and residential codes for Kentucky. This is why western Kentucky, Paducah in particular, has a higher seismic design value in the International Building Code than San Francisco or Los Angeles do (Fig. 4). KGS staff were able to identify the problems with the national seismic hazard maps through research, which led to seismic design values in the Kentucky Residential Code being revised. Earthquake research at KGS has helped state government agencies, local governments, nongovernmental organizations, and the public to develop appropriate mitigation measures for reducing potential earthquake losses in Kentucky. Thus, our earthquake research matters.

Figure 4. Comparison of the short-period design response acceleration for California (a) with that for the central United States (b) in the 2012 International Building Code.

 

Last Modified on 2017-09-19
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