My former employer, Swiss Re, hosted a forum to discuss the issues around the New Madrid Seismic Zone. This area in the Midwest includes Memphis and St. Louis and while the probability of a major New Madrid earthquake is less than that for one in the San Andreas Fault zone, the catastrophic consequences in the Midwest are potentially greater than those of California. This is, in part, because of the economic dependence on transportation systems, power infrastructure and other critical facilities in that area. Experts believe that the loss potential of a major earthquake at New Madrid could range from $80 billion to $200 billion in damages. Indeed, over a period of just under two months in 1811 – 1812, three major earthquakes of a 7.7 magnitude occurred in New Madrid. This was the last major seismic activity in that area and it was second in severity only to the 1906 earthquake in San Francisco. By comparison, the Northridge Earthquake measured 6.7 on the Richter scale. Isn’t it extraordinary to think that an earthquake in the Midwest, an area we don’t typically associate with that peril, exceeded the strongest severity U.S. earthquake in our lifetime?
One of the speakers at the Forum was Chris Cramer, PhD and Research Associate Professor at the Center for Earthquake Research and Information, who made a number of interesting observations concerning the differences between New Madrid and San Andreas. It is more difficult to collect data from the New Madrid Zone, as the surface fault lines are not as readily available to study as they are in California. Dr. Erdem Karaca of Swiss Re added that, the challenges in collecting complete data notwithstanding, it is known that the soils of the Midwest are very different from those of California, with a greater risk of damage due to liquification, which often results in building settlement damages. Another concern raised by Mr. Michael Griffin, PE, a structural engineer with the CCS Group Inc., is that building construction methodology and local building codes are less robust, with respect to earthquake safety, than in California. In California, many of the more vulnerable buildings have been replaced with structures that are more resilient to seismic shifts.
Moreover, earthquakes originating in the Midwest may travel farther than would be possible in California, owing to the fact that the earth’s crust is older and more stable in the New Madrid Zone. For example, an earthquake with an intensity of 7.0 in San Francisco may cover 12,000 square miles, while the same earthquake intensity at New Madrid may cover 203,000 square miles. This larger zone impact brings additional challenges to coordination among emergency responders. In his presentation to the Forum, Jim Wilkinson, Executive Director of Central U.S. Earthquake Consortium, noted that the New Madrid Seismic Zone covers four FEMA zones, eight states and nine bordering states. The Central United States Earthquake Consortium was formed to help coordinate various governmental and private activities related to the New Madrid Seismic Zone. Mr. Andy Castaldi, Senior Vice President of Swiss Re and Head of Cat Perils in the Americas, moderated the Forum. In the near future, I will invite an expert to contribute a guest blog on earthquake risks for the benefit of our small businesses in the Midwest.
