In 2013, a video shot in Terrace, a city in British Columbia, Canada, started doing the rounds in media for capturing bizarre noises that resonated through the streets. The city council later claimed that it was a city worker grinding down a grader blade, but the uploader of the video is still not convinced with the council’s explanation.

According to, over 40 similar incidents have been reported in the U.K, U.S, and other countries till date.

So what are these strange noises?

For centuries, loud, unsettling noises coming from the sky have been reported worldwide.

These noises are caused by a rare atmospheric phenomenon commonly known as ‘skyquakes’ or mystery booms’. Often occurring near coastal areas, sky quakes are characterised by unexplained unnatural noises coming from the sky.

Different countries use different terms to describe this unusual phenomenon. In Italian they are called “brontidi”, i.e.; thunder-like; Japanese call them uminari, which translates to "the rumbling of the sea”; in Dutch they are "mistpoeffers"; People in U.S call them “skyquakes”, but in North and South Carolina, they are known as “Seneca guns”.

What causes skyquakes?

Famous 19th century American author Washington Irving once penned a story on sky quakes in which he jokingly attributed the anomalous noise to ghosts playing nine-pin bowling in the mountains.

On a serious note, some skyquakes are said to have human origins. For instance, when a military aircraft breaks the sound barrier causing a sonic boom. Other theories suggest that the mystery booms might be caused by high-tension electric power lines, electromagnetic radiation, high-pressure gas lines or wireless communication devices.

Meanwhile, some researchers believe that the mystery booms might be triggered by natural phenomena such as tidal waves, earthquakes, electromagnetic noise from auroras and radiation belts, and even Sand Dunes.

“Under proper circumstances, sand dunes are capable of producing a variety of low-level whispering, whistling, singing, humming, or squeaking sounds, and less commonly, loud booming sounds,” writes David Hill, Scientist Emeritus with the US Geological Survey, in a scientific review paper on the causes of skyquakes.

However, Hill added that how these sand dunes produce the noise is still unknown.

Conspiracy theories surrounding skyquakes

In a 1981 book called ‘UFO Contact from Reticulum- A Report of the Investigation’. Author Wendelle Stevens speculated that UFO sightings might have something to do with skyquakes. So much so, co-author William J. Herrman himself claimed to have experienced the sighting of a UFO craft in conjunction with an alleged mystery boom:

“The link between these mystery explosions and UFOs is the most exciting new development in this field,” declared noted UFO researcher Robert Cregan, a professor of philosophy at the State University of New York at Albany. And Dr James Harder, professor of engineering at the University of California at Berkeley, commented, “I think it’s entirely possible that UFOs are connected (to these blasts.”

Other conspiracy theories include speculations that skyquakes are caused by covert weapon experimentations carried out by government organisations or some sinister extraterrestrial forces.

Some people also claim that skyquakes heard in forest regions could be the sound of mythical creatures like Bigfoot.

Currently, there is a host of theories and potential explanations for what causes these skyquakes or mystery booms, but none proven so far.