Skyquakes refer to a mysterious acoustic phenomenon characterized by loud, booming or rumbling sounds that seem to originate from the sky without any immediately identifiable source. These sonic events have been reported globally for centuries, often startling witnesses with their resemblance to distant artillery fire or an explosion. The term describes an atmospheric disturbance that produces a powerful sound wave, frequently heard in coastal areas or near large bodies of water. The persistent lack of a clear, visible origin defines the skyquake and prompts ongoing scientific investigation.
Defining the Phenomenon
The auditory experience of a skyquake is described as a deep, low-frequency boom that can cause noticeable vibrations in windows and structures. Witnesses often report a rattling sensation accompanying the sound, which is similar to a sonic boom but occurs when no aircraft is visible. Historically, these sounds have been given various regional names, such as “Barisal guns” in the Bay of Bengal, “mistpouffers” in Belgium, and “Seneca guns” near New York’s Finger Lakes.
The geographical distribution of these reports tends to concentrate along coastlines and near large inland lakes, suggesting a connection between the phenomenon and large bodies of water. A defining characteristic is the absence of any visible atmospheric event, such as lightning or an obvious local explosion, that would account for the magnitude of the noise. The sounds can occur sporadically over years or in clusters over several days.
Leading Scientific Hypotheses
One scientific theory attributes some skyquakes to bolides, which are meteors that explode in the atmosphere, creating a powerful sonic boom. When these space rocks enter the atmosphere, they detonate high above the ground, producing a shockwave that travels far. The transient nature of these explosions and the lack of physical evidence reaching the ground make them a plausible source for many events.
Atmospheric and oceanic dynamics also offer potential explanations for these booms. Thermal inversions can create an acoustic duct, which acts like a channel to focus and carry sound waves over immense distances. This ducting can amplify distant noises, such as breaking ocean waves or far-off storms, making them sound like they originated directly overhead. Additionally, some researchers suggest that the sudden release of trapped gases, like methane from lake sediments, could generate an explosive sound as it bursts forth.
A third category of hypotheses involves Earth-based processes, specifically seismic activity. Shallow earthquakes, occurring less than a few miles deep, can generate intense acoustic energy that propagates through the atmosphere with minimal ground shaking. Recent research using atmospheric sensors and seismographs has often failed to find a correlation between reported skyquakes and local earthquake activity, suggesting that many of the booms are purely atmospheric in origin.
Differentiating from Known Local Noises
True skyquakes are distinguished by their lack of clear attribution, setting them apart from many common sources of loud noise. Man-made sounds, such as military sonic booms from supersonic aircraft, are often a cause of localized booming, but historical reports of skyquakes predate the invention of supersonic flight. Similarly, quarry blasts or industrial explosions are localized events that can be traced to a specific time and place of operation.
Natural phenomena like distant thunder are also sometimes mistaken for skyquakes, but thunder is usually accompanied by observable weather patterns capable of producing lightning. A defining trait of a skyquake is the report of a loud boom under clear or non-stormy skies. Furthermore, a local, shallow earthquake would be registered on nearby seismographs, whereas many skyquakes occur without any corresponding seismic data.