Most people are familiar with earthquakes, since almost 55 seismic tremors happen around the world in a single day. However, there is actually another phenomenon called skyquakes which are louder and not nearly as predictable.
What Are Skyquakes?
Skyquakes are enigmatic sounds described as a very loud bang that seem to come from the sky. While a sonic boom is brought by an object that breaks the sound barrier, a skyquake is characterized as a boom that happens with no apparent cause.
The sound produced by a skyquake is like a distant, very loud thunder with no clouds in the sky. Sometimes, it is likened to the sound of cannon fire. The trumpet-sounding noise can be so loud that it can cause vibrations in buildings and houses. There are also reports where they cause shock waves that can rattle plates.
Skyquakes are observed all around the world and are called by several names in different countries. They are known as Barisal Guns in India, Uminari in Japan, Retumbos in the Philippines, and Mistpoeffers in the Netherlands and Belgium. In Italy, they are called Lagoni and are associated with lakes.
This phenomenon is also reported in Australia, Germany, Iran, Ireland, Scotland and many regions in the eastern coast of the US where they seem to come from way offshore. In North Carolina, it is known as Lake Guns or Seneca Guns after Seneca Lake in central New York state.
In 2017 alone, there are over 64 different incidents involving loud, unexplained booms reported worldwide. One of them occurred near Daytona Beach, Florida on December 3. A month prior to it, residents of Birmingham, Alabama experienced a similar event which was dubbed by the media as "Bama Boom".
No one has been able to record the loudness of a skyquake, but all reports indicate that it is very low frequency. This low frequency and great intensity (>100 dBA) enable skyquakes to rattle buildings.
What Causes Skyquakes?
Experts believe skyquakes have various causes, such as coronal mass ejections, collapsing landmasses, meteors, and escaping gas. They are also described as sounds generated by quarry blasts, distant storms, or secret military operations.
Still, no satisfactory theory can explain all the reported causes of skyquakes. Although sonic booms from aircraft may trigger skyquakes, it is not enough to account for many reports recorded before the supersonic flight was invented.
To narrow down the possible theories, a team of seismologists at the University of North Carolina made preliminary observations on sky quakes. Using the EarthScope Transportable Array, they measured seismic activities in North Carolina between 2013 and 2015. Then, they compared the recorded data with local news reports that mentioned mysterious sounds or similar events.
Although the booms in the sky can cause ground shaking, they did not find any earthquake records that coincided with skyquake events. Because of this, the team concluded that sky quakes are not from seismic activity, which makes them even more mysterious. They presented some ideas for the acoustic phenomena, such as the explosion of meteors above the clouds or the sound of a large crushing wave amplified by the sea.
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