Date: Winter 2011-2012
Why are there earthquakes in Oklahoma? Oklahoma is in the middle of a tectonic plate.
There can still be a build up of strain within a plate. There are
faults in Oklahoma (and other states) along which there may be
earthquakes. There may be folds and fractures, for example, that
may have earthquake activity. Also, a stronger quake along a major
fault like the New Madrid can trigger smaller quakes in other faults
or cause rumbling that you feel in your state.
Here is a link to the US Geologic Survey's earthquake web page for
Oklahoma. There is a section on earthquake history, as well as some
maps that you can look at to learn more.
Have fun learning more about your state's geology.
Patricia Rowe, MS Geology, MSEd
There are several theories as to why the cnetral portions of a continent would have earthquakes. Especially, when the New Madrid fault has generated the largest known earthquake in the North American plate and it is near St. Louis Missouri, practically dead center. Most of the theories center around the idea that the plates has disparancies in the weight distribution and thus causing inequities in the plate's resting in the upper mantle. One talks about glaciers pressing on the northern portions of the plate and many earthquakes are caused by the slow rebonding of the plate from the wieght of the past glacier activity. Another suggests that the Mississippi River drainage system is slowly removing material making the continent lighter and it slow bounces up off the mantle irregularly causing quakes along the numerous fault lines found throughout the plate. Another suggests that the moving mantle is placing forces that could casue quakes. There are other ideas.
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Update: June 2012