Last night the USGS recorded an earthquake of unknown magnitude centered 2 km south of Tampa FL. The FAA was reported as saying this was a sonic boom cased by two F-18 fighter jets approaching MacDill AFB in Tampa. Anyone who has heard a sonic boom before (and living in Florida, we hear quite a few of them between the space shuttle landings and various military bases) will tell you what happened last night was much more than that.
At 7:41 pm EST, my 3-year old son and I were sitting on the couch when our sliding glass doors started to rattle. 10 seconds later the floor started vibrating, enough to send my son into a panic and inquire what was happening. Having been in earthquakes before, I assumed that's what it was. The entire event lasted about 30 seconds, and was felt in several surrounding counties. A sonic boom, no matter what creates it, is never more than a few seconds. I do not recall hearing the classic “thud” that accompanies the subsonic vibration, but I may have missed it…but the vibration lasted a good 25-30 seconds, and was severe enough to register on local seismic monitoring stations. You can varify the event at earthquake.usgs.gov.
Seeing as how the Air Force alerted the FAA with an explanation, you can probably deduce that this was some sort of military test and the F-18 sonic boom was the cover story. The event was reported in at least 8 surrounding counties, which is an area of a few hundred miles. Sonic booms are never heard or felt over an area that large, even when the space shuttle returns from orbit. Whatever it was, the military isn't giving us the full story, and as usual, the media is doing very little to find out what the real facts are. The Air Force spokesman was quoted as saying the jets would be departing either today or Sunday for the return trip, indicating we may have another “sonic boom”.
UPDATE: Actually, I my memory let me down on this one The bomb I was thinking of wasn't the nuclear bunker-buster, which admittedly is deployed out of Florida, but couldn't possibly have had such a small impact. The bomb I was trying to recall the name of is the “21,700-pound satellite-guided GBU-43/B Massive Ordnance Air Blast Bomb, or MOAB” also known as the 'Mother of All Bombs'. That's the one that got test-dropped on Florida in Nov, 2003.