That's when The Great Central US ShakeOut's Indiana drill takes place. No matter what the "psychics" and pop prognosticators claim, there is no sure way to predict an earthquake. It can happen at any time, and with no advance notice. At least when a tornado occurs, we generally have some time to get to a safe place. Earthquake preparedness is not to be put off; it can literally be the difference between life and death for thousands of your neighbors in the Hoosier state.
From the ShakeOut site:
Indiana has several faults, but, unlike California’s famous San Andreas Fault, nearly all of our faults are buried and can’t be seen at the surface. Researchers have been able to map some faults in Indiana using evidence found in rocks from oil and gas wells and by employing a method called reflection seismic profiling. This method involves recording man-made vibrations reflected off layers of rock below the surface. Most of the faults that have been mapped in Indiana are located in the southwestern corner of the state. These faults extend into Illinois and are collectively known as the Wabash Valley Fault System.The Indiana Geological Survey also offers an EarthQuake Hazard Map, showing which areas in Indiana are at the greatest danger of liquefaction. Unconsolidated sediment proves to be an effective medium for amplifying the waves of an earthquake, increasing the potential for damage. The soil which seems so solid under our feet starts to act like a liquid. A nifty demonstration of this, using a wheelbarrow, was created by a denizen of Christchurch, NZ after their recent earthquake.
The ShakeOut site also includes this video, illustrating how a drill is executed.
Indiana Department of Homeland Security's earthquake preparedness page
The Great Central US Shakeout's Indiana site