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• April 9, 1952: A damaging earthquake centered near El Reno, Oklahoma, affected a total
area of 140,000 square miles, including the entire eastern half of Kansas. The magnitude
5.5 shock was felt in Kansas most strongly at Medicine Lodge. KC was also strongly
affected.
• March 18, 1927: An earthquake near White Cloud, in the extreme northeastern portion of
the state, rocked houses such that people rushed out of them.
• January 7, 1906: A magnitude 4.7 earthquake affected an area of about 10,000 square
miles in Kansas, Missouri, and Nebraska. Chimneys were thrown down and some cracks in
walls were observed at Manhattan. Houses and buildings vibrated at Topeka, where a loud
roaring sound was also heard. A series of small aftershocks were felt in Manhattan.
• October 31, 1895: This earthquake near Charleston, Missouri, affected a million square
miles over 23 states. The strongest effects in Kansas were reported in Topeka.
• November 8, 1875: A moderate earthquake near Valley Falls north of Topeka was felt over
8,000 square miles but did little damage.
Extent
Overall, Region L is in a low seismic activity area. The Nemaha fault would directly affect Riley
and Pottawatomie Counties, and the New Madrid Seismic Zone follows the Mississippi River
valley and is not expected to cause Region L any significant damage. Missourian’s trying to
escape the carnage of the New Madrid Fault having a seismic event could inundate the Region,
leading to sheltering and feeding issues. The magnitude of an earthquake in the planning area
has been determined to be limited. Injuries and illnesses would not result in permanent
disability, and shutdown of critical facilities would not last for more than a week. Approximately
10 – 25% of property could be severely damaged.
Probability of Future Hazard Events
Figure 3.15 below depicts the probability that ground motion will reach a certain level during an
earthquake. The data shows peak horizontal ground acceleration (the fastest measured change
in speed for a particle at ground level that is moving horizontally because of an earthquake).
The shaking level that has a 10 percent chance of being exceeded over a period of 50 years,
which is more of a worst-case scenario, depicts the shaking level that has a 2 percent chance of
being exceeded over a period of 50 years. Typically, significant earthquake damage occurs
when accelerations are greater than 30% of gravity.
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