What on Earth Are Skyquakes?

There are plenty of potential reasons for a boom to rumble through the air, but skyquakes don't seem to be attached to any of the usual suspects. Learn more about these mysterious phenomena on BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works. Hi brain Stuff,
Lauren boblebam here. One November afternoon, in residents of fifteen
Alabama counties were reportedly startled by a loud boom that
caused some to call nine one one operators in alarm.
As the National Weather Services Birmingham station tweeted not quite

(00:22):
a couple hours later, there wasn't any clear explanation for
the noise. Radar scans and satellite imagery of the region
didn't show any large fires or smoke from an explosion,
and the U S Geological Survey didn't spot any signs
of an earthquake on its seizemic monitoring system. In their tweet,
the National Weather Service speculated that the sound may have
been caused by an aircraft or meteor, but said we

(00:43):
don't have an answer and we can only hypothesize with you.
A NASA scientist soon knocked down those possible explanations. Bill Cook,
head of these space agencies Meteoroid Environment office at the
Marshall Space Flight Center in Huntsville, Alabama, told al dot
com that he was skeptical that sound could have been
caused by meteor because there were no reports of anyone
seeing a fireball. Cook also discounted the possibility that the

(01:06):
boom had been created by an aircraft, noting that the
seismic signature is not characteristic of that produced by supersonic jets.
Boom about six hundred miles or nine and seven kilometers
to the north in Ontario, Canada, the Elgin Field infrasound
array picked up an infrasound wave that apparently was linked
to the boom. It usually takes something pretty big, such

(01:26):
as a severe storm and avalanche or a rocket launch
to trigger such a wave. To add to the weirdness,
less than two weeks later, another similarly unexplained boom was
heard one morning in the Birmingham area. We spoke with
James Cooker, director of the Jefferson County, Alabama Emergency Management Agency,
via email. He said that he heard a double boom,
although the sound I heard may have included an echo

(01:49):
caused by the mountains, he said, and Alabama isn't the
only place where things have been booming lately. Skyquakes as
they're commonly called, recently have been heard across the US
in stay ranging from New Jersey to Idaho, as well
as in places as far away as India, where two
seaside resort towns were jolted in August by a boom
so loud that it shattered hotel windows, according to the

(02:10):
Dacca Tribune. Indeed, as u S Geological Survey scientist emeritus
David Hill detailed in a article on the subject, mysterious
booms have been heard for many years in places across
the world. In Belgium, they're known as MIAs poofer's, while
the Italians call them bron titi. In the vicinity of
Lake Seneca and the Catskill Mountains of New York, residents

(02:30):
have long heard the Seneca guns, a phenomenon that was
described by author James Fenimore Cooper back in eighteen fifty
one as a sound resembling the explosion of a heavy
piece of artillery that can be accounted for by none
of the known laws of nature. As Hill noted in
his article, numerous explanations for skyquakes have been proposed over
the years, including shallow earthquakes that could produce audible sounds

(02:52):
without noticeable shaking, massive tsunami waves breaking far from shore,
explosions of methane gas released from the methyl hydrate beds
sand dunes, shared by avalanches and of course meteors. As
Hill wrote, meteors penetrating the upper atmosphere could create sonic
waves that wouldn't reach Earth's surface until after the meteor
had vanished, so the connection between the two wouldn't be apparent.

(03:14):
People have also raised the possibility that the booms, or
at least some of them, might be caused by tests
a secret U S military aircraft, such as the long
rumored spy plane that aircraft buffs have dubbed Aurora. However,
there may not be one single explanation for all the booms.
Hill explains it is indeed the case that there may
be several plausible explanations for any given incidents of a

(03:36):
mysterious booming sound, and that the environment where the sound
is heard will determine which of the possible explanations are
the most reasonable. A sound heard in the middle of
the desert, for example, is not likely due to breaking surf.
Hill says that most booming sounds are heard over a
limited range, so reports of clusters of booming sounds separated
by large distances are most likely coming from multiple sources.

(03:58):
The exceptions, he says, a main clue the sound from
a meteorite exploding in the atmosphere high above the Earth,
a massive volcanic eruption, or an aircraft flying it's supersonic
speeds for an extended distance. Today's episode was written by
Patrick Jake Haiger and produced by Tristan McNeil. For more

(04:18):
on this and lots of other mysterious topics, visit our
home planet, how stuff Works dot com.