The series of seismic events began with a magnitude-2.4 earthquake on Wednesday morning in Reno County, Kansas, followed by a stronger magnitude-4.2 quake on Friday morning, which over 1,000 people reported feeling.
No severe damage was reported, but some older buildings suffered small cracks after the earthquake. Five more earthquakes, ranging from magnitude 2.4 to 3.1 struck the area on Friday. On Saturday, three more earthquakes of similar magnitude shook the area yet again.
On Sunday morning, Kansas was shaken up by a magnitude 4.1 earthquake, the eleventh earthquake in five days. Experts say an earthquake over magnitude 4.0 is not unreasonable.
"This [4.2] was not unexpected in terms of magnitude. It was not unreasonable based on the recursion situation, the number of 2′s and 3′s you’ve had," said Kansas Geological Survey director Rick Miller, according to the Kansas City Star.
According to KWCH12, officials are currently investigating a few possible causes for the quakes, including wastewater from injection wells.
An article in the 1956 Bulletin of the Seismological Society of America recorded two moderately strong earthquakes since 1867: one in 1867 and one in 1906. The article stated that a moderately strong earthquake is expected to occur in Kansas about every 40 to 45 years.