Mysterious booms, bangs and shudders have been reported on Unknown Country for years, and they continue to be a phenomenon that we monitor with a keen interest.

The unexplained noises have been heard all across the globe, including Canada, Brazil, Ukraine, Spain, South America, Russia, many areas of the United States and across the United Kingdom. Now it seems as though the booms have traveled "down under" as a series of strange "explosions" have been heard across west and north Auckland, in New Zealand.

A local Facebook page was inundated with 450 comments, reporting booms and shakes from Stanmore Bay to Stillwater. The local authorities are mystified by the noises, which began at around 4pm in Arkles Bay and were still being heard at around 5pm in the Hibiscus Coast area. Inspector Tony Edwards of police northern communications said reports had been received from Herald Island, describing loud bangs like gun shots or some form of detonation, along with shaking that rocked houses in the affected locations.
Tectonic activity was ruled out by Geonet; utility companies could not find any form of electrical disturbance and the air force denied that aircraft were involved.

Experts even looked to the heavens to provide the answer: Astronomer Alan Gilmore, at Tekapo’s Mt John Observatory, theorized that the booms could be meteors creating sonic booms, as several loud bollide incidents had previously occurred in New Zealand, but he had to discount the theory when multiple booms were reported. It was very unlikely that several meteors would strike in succession across such a small area, he said, adding "I think you’ll have to look for a terrestrial explanation."

This is not the first time that New Zealand has experienced the boom phenomena. Back in 2006, Unknown Country reported booms across the country that seemed to be associated with sightings of a large, mystery cat,  an odd occurrence in a country that has no indigenous panthers, lions, tigers, leopards or wolves.

Elsewhere, the booms returned to Kentucky and Illinois earlier this year, when residents reported hearing the noises for two days in a row. The inexplicable sounds were accompanied by the now typical strong vibrations, leaving police and a number of public safety investigators baffled. The usual meteor strikes, seismic activity and sonic booms have again been ruled out as explanations, along with quarrying explosions or fracking activity.

Jason Lindsey from "Hooked On Science" has researched the booms with geologists, and suggested a couple of other theories that could explain the vibrations.

"Up in the Northwest, they had reports of these booms going on a few years back, and it turned out to be shallow earthquakes happening close to the surface. Instead of doing the damage and the rocking and rolling that you sometimes experience with an earthquake, you get more of a boom with maybe the windows shaking."

Lindsay’s second theory revolves around the concept of "frost quakes":

"A frost quake happens whenever the temperatures drastically drop within a short period of time and there’s water in the soil," Lindsey said. "That sudden drop causes the water to freeze and expand, cracking the rocks underground. Sometimes that can create what people hear as booms."

These ideas are still conjecture, however, and do not explain the vast number of other similar noises and judders that have been heard and felt around the world. The widespread yet consistent nature of the sounds adds to the mystery though, in other incidents, the noises have been described as "trumpeting".

Until a definitive answer is found, the booms continue to intrigue affected populations, and the rest of us. Do you have any ideas what could be causing these unnerving events? Subscribers can share their views with us – join our unique online community today!