It was not an earthquake: booms, blasts and other bangs
You felt or heard something, you checked, and nothing was recorded. That happens a lot, and the answer is usually not "the catalogue missed it". A number of ordinary things shake a house, and some of them are catalogued by USGS alongside earthquakes.
Check your location first → — and remember that a small earthquake can take several minutes to appear, so "nothing yet" is not the same as "nothing".
The most useful distinction: a bang or a rumble?
It is not a rule, but it is a good first filter.
- A single sharp bang, with little or no rolling, and maybe a rattle of windows, is more often a sonic boom, a blast, or something structural.
- A rumble, a rolling motion, or shaking that builds and fades over several seconds is more characteristic of an earthquake — you feel the waves arrive separately.
Small, very shallow earthquakes can also be heard as a bang, so this filter is imperfect in exactly the direction that matters. Checking the record is better than reasoning from the sensation.
What USGS actually catalogues besides earthquakes
Seismic networks record ground motion, not earthquakes specifically, so anything that shakes the ground hard enough gets recorded and classified. USGS event types include quarry blasts, mining explosions, chemical explosions, nuclear explosions, rock bursts, landslides, rockslides, ice quakes, sonic booms and acoustic noise.
QuakeIndex labels these as what they are. If the event you find is a quarry blast, the page says so in plain words rather than calling it an earthquake, and it is never offered to search engines — a page about a quarry blast has no lasting value and hundreds of them would only dilute the index.
The usual suspects
| Cause | What it feels like | Clues |
|---|---|---|
| Sonic boom | One or two sharp bangs; windows rattle; no rolling | Near military training routes and coastlines. Often reported over a long, narrow corridor rather than a circle. |
| Quarry or mining blast | A thump, sometimes with a short rumble | Weekday working hours, and repeating on a similar schedule. Sometimes catalogued by USGS, so worth searching. |
| Heavy vehicle or construction | Localised shaking, often rhythmic | Only you and your immediate neighbours notice it. |
| Water hammer or plumbing | A bang inside the walls | Coincides with a tap, a washing machine or a toilet refilling. |
| Thermal expansion of a building | A single crack or pop from the roof or frame | Early evening as things cool, or on a hot afternoon. |
| Frost quake (cryoseism) | A loud bang and a brief jolt | Deep winter, after a sharp temperature drop, in wet ground. Northern states. |
| Landslide or rockfall | A rumble | Steep terrain, often after heavy rain. USGS catalogues larger ones. |
| Thunder | A bang and a rattle | Easy to dismiss, and genuinely mistaken for an earthquake when the storm is distant and the sky overhead is clear. |
How to settle it
- Check the record for your location over the last hour.
- Wait ten minutes and check again. Small events in sparsely instrumented areas take longer to appear.
- If you felt shaking and nothing is listed, file a Did You Feel It? report with USGS. Multiple reports from an area are itself a signal, and for small events they are sometimes the best evidence that exists.
- Check whether anyone nearby noticed. A sonic boom is heard over a wide corridor; a water hammer is heard by one household.
Why "was that an earthquake?" is a hard question to answer well
Because the honest answer in the first few minutes is often "we do not know yet", and that is unsatisfying enough that most sites give a confident no instead. Our felt page and API distinguish three answers rather than two, and the middle one — nothing recorded yet, which is not a no — is the whole reason the page exists.
Sources
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