Mysterious noises, often compared to rolling thunder or distant cannon fire, are frequently heard off the Cape Fear coast and the Myrtle Beach area. Although reported regularly at points up and down the Eastern Seaboard, Seneca guns seem particularly concentrated off the Carolinas.

To date, no satisfactory scientific explanation for the phenomenon has been found.

The name “Seneca Guns” seems to come from Seneca Lake in upstate New York, where the sounds are often heard. In 1850, James Fenimore Cooper (author of “Last of the Mohicans”) wrote a story, “The Lake Gun,” describing the phenomenon, which seems to have popularized the term. (An alternate explanation, linking “Seneca Guns” to an obscure Civil War battle in Seneca, Ga., seems dubious.)

The sounds are heard in coastal areas; observers insist they are never heard at sea. In 2005 and 2008, residents in Brunswick County reported they were loud enough to rattle windows and shake houses. In December 2001, a Seneca gun event prompted more than 100 calls to New Hanover County authorities. No serious damage, however, has ever been attributed to a Seneca gun.

Some Seneca gun events are attributed to military jets breaking the sound barrier, but the phenomenon has been reported in this area periodically since at least the 1850s, well before the air age. Southport historian Susie Carson insisted that the noises are most common in fall, although reports have been logged at all times of the year.

In 2005, Tyler Clark, chief geologist with the N.C. Geological Survey, guessed that the most likely cause for Seneca guns would be shallow earthquakes occurring offshore. The problem, according to the U.S. Geological Survey, is that many Seneca gun reports cannot be connected to quakes detected by seismographs. Seneca gun-like noises were reported, however, in connection with the Charleston, S.C., earthquake of 1886.

Peter Malin, a seismologist formerly with Duke University, speculates that the “guns” are somehow atmospheric in origin; his experience suggests the vibrations come from above ground level, rather than below. In the summer of 2001, Malin installed a seismograph in a 1,300-foot bore hole near the Fort Fisher State Historic Site, in an effort to detect mini-quakes; the project was never properly funded, though, and Malin was never able to record any results.

The “guns” seem connected to similar phenomena heard in different parts of the world, such as the “Barisal guns” in parts of India and Bangladesh, the “uminari” of Japan and the “mistpouffers” on the coast of the Netherlands and Belgium.

Explanations as exotic as UFOs and the angry ghosts of Indians have been put forward.

The U.S. Geological Survey Web site rules out a few causes: Tidal waves (none reported in connection with Seneca guns), lightning (Seneca guns often occur during clear skies in fair weather), shifts in tectonic plates (the nearest plate boundaries to Southeastern North Carolina are hundreds of miles away, in the mid-Atlantic and Caribbean), loud meteors called bolides (might explain some but not all of the guns), landslides off the continental shelf (none reported during recorded history), sink holes forming (not enough limestone deposits in the area, although plenty of sink holes occur near Boiling Spring Lakes in Brunswick County), cold air meeting warm Gulf Stream air (no explanation for how this could cause booming noises) or pockets of air, trapped underground being released (such seepage rarely makes a sound).

Several people have suggested that the noises may be caused by the release of bubbles of methane; deposits of methane clathrate hydrate are known to occur in the area. Again, however, methane seepage does not usually cause a noise, and it does not come up in large enough quantities to cause explosions.

Residents feel a shake, but geologist says it wasn’t an earthquake

Have you heard the area’s mysterious booms recently? Tell us where you were (and see the map)