In January, reports came from Adair and LeFlore Counties (Oklahoma) regarding inexplicable vibrations that could be felt as well as heard. Similar reports came from residents across the border in Arkansas as well. The sound had been described uniformly as a distant rumble.
After checking with local mining companies, Sequoyah County sheriff Ron Lockhart rule out blasting as the cause. The mystery was further compounded when local news media, 40/29 News, reported that the noise wasn't the result of ordinance testing by local military installations.
The strangest data (or lack thereof) came from the Oklahoma Geological Survey, which determined that no tremors had been detected that corresponded to these reported rumblings. Some have postulated that, if the atmospheric conditions were just right, the concussive rumbling of military ordinances could travel nearly 100 miles, which they did years before. A weapons demonstration, taking place near Ft. Sill, in the Wichita Mountains, was heard 80 miles away.
However, this isn't the only place strange rumblings have been heard - or the only time.
Nearly a month later, in Minneapolis, MN, reports had come in of similarly inexplicable "explosions". Beginning just after Valentine's Day, in the early hours of Sunday, February 15, residents such as Matt Gross heard a loud bang that seemed to come from 20 blocks away. Over the next 24 hours, three loud explosions were heard and reported by a number of locals.
But this wasn't an isolated case. Over the past year over 100 booms had been reported in the Minneapolis area. Most of these were at night and usually on a Wednesday or Friday. Nearly half of these reports are centered on the Mississippi River, between Lake Street and Ford Bridge.
Lt. Dean Christiansen, who is investigating the mystery, believes most are will remain unexplained. Although theories have been presented, from fireworks to terrorism (catching the eye of Homeland Security at one point), no one has been arrested and the booms haven't been explained adequately.
Are explanations such as exploding transformers likely? Perhaps in explaining at least some of them, yes. It is likely to assume that at the height of the booms, someone mistook at least one transformer explosion for this strange phenomena. But, in digging deeper, we learn that the noise has been heard far back in time, prior to exploding transformers.
What sounds to some like cannon fire has been reported around Rabun County, Georgia for generations. These blasts are often preceded by a screeching or keening sound, like babies wailing. They are, like the Minneapolis mystery, often heard at night.
The first written account comes from an 1897 issue of the Monthly Weather Review. Two men were camped atop Rabun Bald, the highest mountain in the area. At around 10 o'clock that evening, a booming began that lasted for several minutes and seemed to be coming from the earth itself. Every so often, throughout the night, the sound would begin again and cycle for a few minutes before receding once more.
Upon returning to town, locals told them it was probably bears rolling boulders down the hillsides as they searched for hidden grub worms and insects. But years later, after Black Bears had been hunted to near-extinction, the blasts were reported still - often by tourists trekking the new highways that had finally pierced the forbidden backwoods of Georgia. These travelers, from other states would never have heard the local legends and likely didn't make up the tales they told.
Heading north, one can find the "Seneca Guns" of the North Carolina coast, which have been known to rattle windows and doors. These booms differ somewhat in that they are only heard during the day. Reputable people like Jim Lanier, one-time director of the North Carolina Aquarium in Ft. Fisher, have reported hearing the eerie sounds. He said it sounded like artillery fire.
But, once again, no military explanations panned out. Other scientists have, however, pinned the blame on large chunks of the continental shelf eroding in to the depths offshore. Lanier dismisses this theory, citing that the slope in this area is far to gentle to break off in large sections.
What explanation (or explanations) exist to lay these mysterious rumbles and booms to rest? Are as-yet-known seismic forces at work, or does the answer lie in the acoustic anomalies of our atmosphere? Perhaps it is another meme that arises from our collective imagination, but if so, we must congratulate ourselves on dispersing the legend so widely.