Skyquakes and Mistpouffers

Summary

A boom, like distant artillery. It shakes windows. There is no aircraft, no storm, no explosion, and often no seismic record of anything at all.

People have been reporting this for centuries, from a great many places, and the places have their own names for it. The Belgians call them mistpouffers, fog belches. In New York they are the Seneca Guns. In Bengal they were the Barisal Guns. In Japan, uminari.

Here is the registry's finding, and it is the same finding it reached about the Hum, and it is not a satisfying one.

There is no such thing as a skyquake. There is a word, and the word has been applied to a large number of separate phenomena with separate causes, and several of those causes are now known, and treating the whole collection as one mystery has guaranteed that it will never be solved.

What is documented

The reports. Booming or detonating sounds, unaccompanied by any visible cause, sometimes strong enough to rattle windows and shake buildings, reported across centuries and continents.

The regional names. Mistpouffers along the North Sea coasts. The Seneca Guns, reported around Seneca Lake in New York and, quite separately, along the coast of the Carolinas. The Barisal Guns of the Ganges delta. Uminari in Japan. There are many more.

James Fenimore Cooper wrote about the Seneca Guns. The mistpouffers were debated in the correspondence pages of Nature in 1895. This is not new.

The recurring feature. In many cases, no seismic instrument records anything of significance, and no source can be identified at the time.

Leading explanations

Several. And the crucial point is that they are all correct, for different events.

Sonic booms. Military aircraft going supersonic produce a shockwave that reaches the ground as a boom, and can do so from a very long way away and from an aircraft that is never seen. This accounts for a substantial share of reports, particularly near coasts, near military ranges, and near training corridors. An investigation by the US Naval Research Laboratory, reporting in 1978, attributed most of a wave of booms along the American East Coast to supersonic military aircraft offshore, although many events could not be explained this way.

Small, shallow earthquakes. A small earthquake very close to the surface can produce an audible boom while generating almost no perceptible ground motion. It is not that no earthquake occurred. It is that the earthquake was small enough, and shallow enough, that you heard it rather than felt it. The USGS has documented booms accompanying a swarm of small, shallow earthquakes at Spokane in 2001, and considers that at least some East Coast booms are probably associated with very small earthquakes, although those booms have not been directly studied.

Bolides. A meteor entering the atmosphere and breaking up produces a shockwave and a boom. It happens frequently. If the object breaks up in daylight or behind cloud, nobody sees anything and everybody hears something.

Gas release from sediments. Methane escaping from seabed or delta sediments, and in some proposals detonating or producing acoustic pulses. This is a serious candidate for the coastal and deltaic cases, including the Barisal Guns, and it has not been fully established.

Atmospheric ducting. Sound, like light, can be trapped and carried by temperature inversions. A distant, entirely ordinary noise, a quarry blast, a gun range, an industrial process, can be carried tens or hundreds of kilometres and delivered to a place where nobody can imagine what produced it, arriving from a direction that makes no sense.

This is the same mechanism that produces the Min Min lights. (See AR-0018.) The atmosphere is not a passive medium. It is a lens and a waveguide, and it will deliver things to you from over the horizon.

Current status

Partially explained. Many individual events have been attributed with confidence. Many have not, principally because nobody investigated them at the time and there is nothing left to investigate.

At Seneca Lake itself, a 2025 study by Cornell University, the SUNY College of Environmental Science and Forestry and the New York State Department of Environmental Conservation sampled large pockmarks on the lake bed to test whether escaping methane explains the local booms. Methane was present, but at the same levels inside the pockmarks as elsewhere in the lake, and the cause of the Seneca Lake sounds remains unexplained.

The registry keeps this record and files it with AR-0008, because the two share a structure and the same lesson.

The Hum is not one thing, and skyquakes are not one thing, and in both cases the act of giving a collection of unrelated reports a single memorable name created an entity that then had to be explained, and could not be, because it does not exist.

Naming is not neutral. A name makes a thing, and then the thing has to be accounted for, and people spend a century trying.

Last reviewed: September 2026. Records are provisional. Where the evidence changes, the entry changes. Found an error? Tell us.