The Great ShakeOut is October 16 across the United States. There will be drills for states in the Midwest, the Southeast, California and elsewhere, including overseas. Millions of people have registered their families, schools and businesses to participate, and more are signing up.
The risk of a dam failure or severe damage during an earthquake is well documented. Top-of-mind for most people would be California and its many High-Hazard Potential (HHP) dams. But the HHP dams in other states could be similarly threatened by seismic activity along other fault lines. Missouri, Indiana, Kentucky, Georgia, North Carolina and even Texas have their own earthquake risks. Dams in these and other states need Emergency Action Plans that can be activated immediately if damage is detected.
The U.S. Geological Survey recently updated its earthquake risk map based on more recent quake reporting and using newer modeling technology. The western United States faces a high risk of damaging earthquakes up and down the coast and in the intermountain region, the report said. The California cities of San Jose, Vallejo and San Diego all saw a heightened threat, as new fault lines have been recently discovered, the report said. USGS also upgraded the risks facing parts of the central and eastern United States, singling out areas near New Madrid, Missouri, and Charleston, South Carolina. The 16 states with areas facing the highest risk are Alaska, Arkansas, California, Hawaii, Idaho, Illinois, Kentucky, Missouri, Montana, Nevada, Oregon, South Carolina, Tennessee, Utah, Washington, and Wyoming.
Earthquakes don’t have to be “the big one” to cause cracks and leaks in dams, especially older or poorly maintained ones. The bigger the quake, the more likely the failure. If more dams have an EAP by the time of the earthquake drill, emergency response officials can include a simulated exercise of those EAPs. After the drill, the EAPs would contribute to readiness for any type of emergency at those dams. Some areas most at risk may have numerous dams that are not HHP but that, if breached, could cause flooding that would hamper the recovery effort.
Great ShakeOut drills assume a major earthquake has happened. The drills provide an opportunity to assess risk to infrastructure of all kinds, learn more about mitigating those risks, and test emergency response systems. For businesses and families the self-led drills are an opportunity to practice how to “Drop, Cover, and Hold On.” Endorsed by emergency officials and first responders, the proper response to an earthquake is to:
- Drop to the ground
- Take Cover under a sturdy table or desk if possible, protecting your head and neck and,
- Hold On until the shaking stops
Led by the Federal Emergency Management Agency (FEMA), the Central U.S. ShakeOut is coordinated by the Central United States Earthquake Consortium (CUSEC), based in Memphis, Tennessee. CUSEC participants include the U.S. Department of Homeland Security and other federal departments, agencies from Missouri and seven other states, universities, and non-governmental emergency response and support organizations.
If you miss out on this year’s earthquake drills, plan to participate next year. The drills now are held every year on the third Thursday of October.
Scientists Study What May Happen in the Midwest
Last January U.S. Geological Survey (USGS) scientists confirmed that the New Madrid fault zone is active and could spawn future large earthquakes. The zone stretches 150 miles, crossing parts of Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee. In 1811 and 1812 three earthquakes of magnitudes 7.5 to 7.7 hit the area, but it was sparsely populated.
Previous studies have suggested that the New Madrid may be shutting down, based on readings that showed little strain accumulation at the surface. Other research blamed ongoing quake activity on aftershocks from the 1800s, which would essentially relieve strain on the fault.
The latest study, published in Science magazine, suggests otherwise. USGS geophysicists analyzed past quakes in the New Madrid region and used computer modeling to determine that the continuing tremors are not related to the big quakes two centuries ago. USGS seismologist Susan Hough told the Associated Press: “Our new results tell us that something is going on there, and therefore a repeat of the 1811-1812 sequence is possible.” The USGS estimates there’s a 7 to 10 percent chance of that happening in the next 50 years.
The National Science Foundation’s Mid-America Earthquake Center (MAEC) at the University of Illinois Urbana-Champaign has developed a highly detailed report on the probable impact in several states if there were an earthquake along the New Madrid Fault similar in severity to the one two hundred years ago. More than two dozen Missouri dams are likely to be damaged in an earthquake centered in southeast Missouri. While most flooding would be from the collapse of levee systems, the failure of HHP dams could add to the death toll and suffering. EAPs can help local emergency responders react promptly to emergencies at HHP dams at any time, not just after an earthquake.
MAEC found that a 7.7 magnitude New Madrid quake would kill thousands of people, leave hundreds of thousands homeless, stranded and in need of relocation for long periods of time. Missouri would have extensive destruction of vital water, sewer, energy and other services, broken transportation systems, failure of communications infrastructure, and interruption of emergency and medical services. Economic losses throughout the region impacted by the quake were estimated at $300 billion, with most of this in Missouri, Tennessee, Kentucky and Arkansas.