What the hell was that?

On April 4th of this year, a loud boom shook much of San Diego for a few seconds. I can honestly say that I didn't feel anything, but many people around here did. Apparently no one knows what caused the disturbance, so theories abound. The San Diego Union Tribune is trying to get to the bottom of it:

Whatever it was, it caused a woman's bed to shake in Lakeside. It created waves in a backyard pool in Carmel Valley. It set off car alarms in Kearny Mesa and rattled windows from Mission Beach to Poway to Vista. At various spots throughout the county, people reported a rumbling sound or a booming noise.

Many theories have surfaced, ranging from earthquakes, military training exercises, rocket launches, sonic booms, meteors, UFO's and top-secret spy planes, but none have any significant weight to them thus far.

Apparently, there have been two unexplained disturbances since January, with one in Maine and another in Alabama. Looking back further has turned up more:

There have been other similar unexplained events over the past few years. Something of the sort happened in Wilmington, N.C., on Dec. 20, 2005; Winston-Salem, N.C., on March 5, 2005; Charleston, S.C., on Aug. 1, 2003; and Pensacola, Fla., on Jan. 13, 2003.

Did you feel it? Do you have any information? The 'Trib wants to know.

Link (via BoingBoing)