That's what 21,000 pounds of bomb sounds like if you're over a mile away, which is how far you need to be in order to escape the blast of the GBU-43B bomb.
The U.S. has dropped the largest non-nuclear bomb in eastern Afghanistan on Thursday only days after a Green Beret was killed fighting ISIS there. The MOAB (Massive Ordinance Air Blast) (aka "Mother Of All Bombs") was initially tested in 2003 but has never been used in combat.
While it was designed for its concussive effect, it will wreak havoc on the caves between Afghanistan and Pakistan (pronounced "Pahkeestahn" by Barack Obama) and has a one mile blast radius.
The reason it was dropped is due to the loosening of the so-called "rules of engagement," which allowed terrorists to escape and got American military killed.