You hear it on the news and you read about in the paper. Oklahoma has experienced increased seismic activity since 2013. According to the Office of the Secretary of Energy & Environment, Oklahoma experienced 109 3 earthquake events in 2013, 579 events in 2014, 903 in 2015 and 623 in 2016. Even in the past 30 days, Chickasha, OK has experienced 12 earthquakes; Noble, OK has 22, and Choctaw 33. These occurrences have raised homeowner's awareness of their homes. Suddenly, those cracks in the brick or sheet rock that went unnoticed are thought to be earthquake damage. They are contacting their insurance agents regarding earthquake coverage. While it's always a great idea to meet with your agent to discuss proper coverage of your home, sometimes the cracks and damage to a foundation started occurring long before the earthquakes began.
Oklahoma soil is red in color because of iron in the clay dirt. Clay is notorious for expanding and contracting during times of saturation and drought respectively. Here is a link to a great video showing the expansion of clay soil after adding water: https://www.youtube.com/watch?v=ACpuYED9WkU. This video was created by Cranfield University but clay is located throughout parts of the US depending on geography.
Now, think about Oklahoma soil. We experience heavy rains and times of drought periodically throughout the year. In 2011, Oklahoma went through a notorious drought where 85% of the state was rated in extreme to exceptional drought according to the National Centers for Environmental Information. During that time, the soil shrank due to lack of water. Michael Kimball of NewsOK published a great article in September 2011 showcasing the effects of the drought on the homes of Oklahoma.
"The exceptional drought strangling Oklahoma's soil has contributed to foundation problems across the state this summer, experts said. The result is a large number of home and business owners facing repairs that are about as expensive as it gets with building maintenance." - Kimball, 2017 http://newsok.com/article/3607166
This almost constant movement to your home is more likely the culprit to foundation damage in Oklahoma. However, no matter what the cause, there are solutions available to homeowners to protect their homes from any additional movement caused by either soil movement or earthquakes.