Skyquake

Key takeaways

Skyquake belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Skyquake to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Skyquake from memory before moving on to harder problems.

Reference excerpt

A skyquake is a phenomenon where a loud sound is reported to originate from the sky. It often manifests as a banging, reoccurring thunderous rumbles (where no storms are active), sonic boom from jet engines (where there are no signs of aircraft), or a horn-like noise. The sound may cause noticeable effects on buildings, including vibration in ceilings or across the walls of a particular room. Those who experience skyquakes typically do not have a clear explanation for what caused them. As a result, they are sometimes perceived as mysterious or supernatural. They have been heard in several locations around the world, typically in areas close to lakes and other bodies of water. Reports of skyquakes have come from the North Sea, the Ganges, Canada, Colombia, Japan, Finland, Vanuatu, Australia, Italy, Ireland, India, The Netherlands, Norway, Tierra del Fuego in Argentina, the United Kingdom, the United States, Mexico, Malaysia (particularly Ipoh) and Indonesia (particularly Jakarta and Java).

Local names Names (according to area) are:

Bangladesh: Barisal guns France: "bombes de mer," "canons de mer". Indonesia: dentuman (lit: "clatter") or suara tembakan meriam (lit: "the sound of cannon fire"). Italy: "brontidi," "marina," "balza," "lagoni," "bomba," "rombo," "boato," "bonnito," "mugghio," "baturlio," "tromba," "rufa." Japan: "uminari" (literally, "cries from the sea") Netherlands and Belgium: "mistpoeffers," "zeepoeffers," "zeedoffers," "mistbommen," "gonzen," "balken," "onderaardse geruchten." Philippines and Iran: "retumbos" United States: "Guns of the Seneca" around Seneca Lake and Cayuga Lake, and Seneca guns in the Southeast US Latin America and Spain: "cielomoto" Canada: "seefahrts" elsewhere: "fog guns," "mistpouffers," "waterguns" In 1804, they were reportedly heard during the Lewis and Clark Expedition near Great Falls. Meriwether Lewis wrote, “[S]ince our arrival at the falls we have repeatedly witnessed a noise which proceeds from a direction a little to the N. of West as loud and resembling precisely the discharge of a piece of ordinance of 6 pounds at the distance of three miles.” William Clark added in his notes, “…a rumbling like Cannon at a great distance is heard to the west of us; the Cause we Can’t account.” They have been reported from an Adriatic island in 1824; Western Australia, South Australia and Victoria in Australia; Belgium; frequently on calm summer days in the Bay of Fundy and Passamaquoddy Bay, New Brunswick, Canada; Lough Neagh in Northern Ireland; Scotland; Cedar Keys, Florida; Franklinville, New York in 1896; and northern Georgia in the United States. Their sound has been described as being like a distant but inordinately loud thunderstorm, occurring even in the absence of any clouds large enough to generate lightning. Those familiar with the sound of cannon fire say the sound is nearly identical. The booms occasionally cause shock waves that rattle dishware. Early white settlers in North America were told by the native Haudenosaunee Iroquois that the booms were the sound of the Great Spirit continuing his work of shaping the earth. The terms "mistpouffers" and "Seneca guns" both originate in Seneca Lake, New York, and refer to the rumble of artillery fire. James Fenimore Cooper, author of The Last of the Mohicans, wrote "The Lake Gun" in 1850, a short story describing the phenomenon heard at Seneca Lake, which seems to have popularized the terms.

Hypotheses Their origin has not been positively identified. Given the long time that they have been known and reported, but with no proposal experimentally confirmed, it seems likely that they occur for more than one reason. Proposed explanations have been:

Moderate-sized meteors causing sonic booms as they strike the lower atmosphere. Gas explosions, either by ignition or sudden release of trapped deposits: Gas escaping from vents in the Earth's surface. With lakes, biogas from decaying vegetation trapped beneath the lake bottoms suddenly bursting forth. (Plausible, since Cayuga Lake and Seneca Lake are large, deep lakes with millennia of deep deposition of organically enriched sediment.) Explosive release of less volatile gases generated as limestone decays in underwater caves. Underwater caves collapsing, and either the released air and/or a wave of water pressure vacuum abruptly arriving at the lake surface. Volcanic eruptions (in places near known volcanic activity). Military aircraft surreptitiously creating sonic booms (this origin does not explain these sounds being heard before the advent of supersonic flight, but this entry could be extended to include military cannon-fire practice). Earthquakes: Shallow earthquakes can generate sound waves with little ground vibration: The "booming" sound is heard only locally, near the epicenter. Avalanches, either natural or human-caused (for avalanche control). Weather: Distant thunder, or loud sounds from wind damage. Atmospheric ducting of distant thunder or other loud sounds from far off. Secondary atmospheric waves from plasma impacts of solar CMEs. CMEs generate plasma shock waves in space, similar to the sonic boom caused by aircraft flying faster than the speed of sound in Earth's atmosphere. The solar wind's equivalent of a sonic boom in the Solar System plasma medium can accelerate protons up to millions of miles per minute – as much as 40 percent of the speed of light. This is a proven source of auroras, but has never yet been shown to be sufficiently forceful and sufficiently abrupt to cause a "boom". Possible resonance from solar and/or Earth magnetic activity inducing sounds. Breaking waves: A line of breaking waves on a rocky shore is capable of producing booming noises at low frequencies, thereby allowing the sound to travel for longer distances.

See also Bell Island Boom, attributed to a lightning superbolt List of meteor air bursts List of unexplained sounds Electrophonic hearing

Notes

References

Worked examples

Example 1 — a first encounter with Skyquake

Start with the simplest possible case. Write down what Skyquake claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Skyquake before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Skyquake ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Skyquake

In research: Skyquake appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Skyquake in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Skyquake is common in secondary-school and first-year university syllabi. It links to neighbouring topics Natural disasters, Types of earthquake, Unexplained phenomena, so understanding it makes those chapters shorter.
In everyday life: Look for Skyquake outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Skyquake in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Skyquake means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Skyquake out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Skyquake in simple terms?

A skyquake is a phenomenon where a loud sound is reported to originate from the sky. It often manifests as a banging, reoccurring thunderous rumbles (where no storms are active), sonic boom from jet engines (where there are no signs of aircraft), or a horn-like noise.

Why does Skyquake matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Skyquake?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Skyquake.