One interesting feature of VERY big explosions, (such as the TSAR Bomb, the eruption of krakatoa, the Tunguska event, etc) is that the sound waves it produces are powerful enough to circle the earth multiple times. This is because of the geometry of the earth - being a sphere, a sound wave sent off in any direction will eventually loop around and return to its point of origin, assuming it is powerful enough.
On a flat earth, the sound waves would travel out and out forever and never cycle back causing the sounds to fall off the edge of the earth. It's essentially the same problem as circumnavigation, but without being able to rely on magnetic compasses and/or Conspiracy-controlled GPS for explanation.
What could cause this?
To save you all the trouble, I have created a few alternate explanations for you. Just pick your favourite and let me know:
1) Bendy Sound.
2) Sound is magnetic and is drawn into circular paths by the magnetic pole.
3) Giant space mirrors that reflect sound.
4) Refuse to acknowledge phenomenon. Demand I generate multi-megaton explosion in order to record sound as evidence for the effect, and insist that until this is done, it constitutes a "win" for FE.
5) Sound is part of the conspiracy.
Thanks