Honestly, I thought it was odd that two significant earthquakes occurred across the country within minutes of each other.
Earthquakes can set off other earthquakes. Earthquakes are a result of built up tension between faults, so the magnitude of one earthquake can hit another fault and release the tension - and walla, you have another earthquake.
Apparently it has a huge underground following.
I see what you did there
PowderHound and TreeNinja