[Diddle E. Squat]

How could a blast be "heard from 40 miles away?"

Because it can? We had an explosion in Deer Park, TX that set off the seismographs at Rice University in Houston, 20 miles away.

[KittyKares]

Drudge has it now.

[Dr. Eckleburg]

...set off the seismographs at Rice University in Houston, 20 miles away.

Seismographs react hundreds of miles away, and are a lot more sensitive than the human ear at 40 miles.

Forty miles for a blast to be audible is amazing.