This mistake always leaves me shaken up.

No! No! No!

In an article about the recent Mt. Carmel, IL, earthquake, CNN wrote, "The epicenter of the earthquake -- the strongest in the region in 40 years -- was about seven miles below ground and 38 miles north-northwest of Evansville, Indiana, the USGS said."

That was wrong. CNN was wrong, period. The epicenter was probably 38 miles north-northwest of Evansville, but it was not seven miles below the ground. The focus likely was seven miles below ground. However, the epicenter is ALWAYS on the SURFACE of the earth. Without exception. Ever. That's what "epicenter" means.