Earthquake Booms, 'Seneca Guns', and Other Sounds - Earthquake "booms" have been reported for a long time, and in the US they tend to occur more in the Northeastern US and along the East Coast. There have been many reports of "booms" that cannot be explained by man-made sources. No one knows for sure, but scientists speculate that these "booms" are probably small shallow earthquakes that are too small to be recorded, but large enough to be felt by people nearby. In New Madrid, Missouri, there are accounts of "artillery-like" sounds that were said to have occurred before or during the New Madrid earthquakes of 1811-1812. [Mystery booms coming from deep in the plate boundary were reported in Indonesia for many months before the December 2004 quake and tsunami.]

Meteors exploding in the atmosphere are a possible cause of other unexplained booms, which are sometimes described as skyquakes.

There does not appear to be any agreement on what causes the booms of the 'Seneca guns'. They have been occurring in several places around the eastern U.S. and in India for at least a century or two.





3/29/2010

OREGON - 3/28/10 - Authorities still don't know the cause of a Southeast Portland boom. It was the second mysterious explosion-like sound to hit the area in two weeks.
Portland authorities have no idea what caused the Sunday night boom that shook a number of residents' homes in Southeast Portland about 8:05 p.m. Many calls came in from the Sellwood neighborhood, but residents from Happy Valley to the Hillsdale area also reported hearing the ruckus. Portland Fire and Rescue sent several crews out, but "nobody could find anything." Portland Fire contacted the airport, but no causes were found there. Police were similarly stumped. There were no reports to confirm that a sonic boom occurred, which some Portland authorities guessed to be the cause. Residents reported a similar incident March 15, and no authorities ended up pinpointing the cause. Some pointed to fireworks as an explanation, but it was never confirmed. The latest one was much louder, and it was "very sudden, very quick." The mystery had the Portland area Twitterverse abuzz, as tweet after tweet referenced the "pdxboom."
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