Rattled by a strong jolt this morning? That wasn’t an earthquake, experts say.
Some residents along the coast from Long Beach to south Orange County felt a strong jolt around 8:22 a.m. Monday, but no significant seismic activity was reported in the region at that time, leaving experts to speculate that it was possibly a sonic boom.
The activity was most strongly felt along the coast in Orange County.
If you are wondering if what you felt was an earthquake, look at the pages for the seismic networks – e.g., https://t.co/LPc4M2DkDn. No quake in Orange County this morning.
— Dr. Lucy Jones (@DrLucyJones) November 15, 2021
The California Institute of Technology on its Twitter page said its seismograms showed no earthquake in Orange County and that “sonic booms are the most common cause of people feeling an event that doesn’t show up in the ground.”
A sonic boom, which sounds similar to thunder, is a blast of energy that occurs when an aircraft flies faster than the speed of sound. It’s typically caused by military aircraft.
A sonic boom occurred earlier this year in San Dimas and was felt throughout Long Beach and Orange County.
Facts about sonic booms from the U.S. Geological Survey:
- Most sonic booms aren’t felt on land (most supersonic training flights are out over the ocean).
- Atmospheric events are difficult to detect with seismographs because they usually transfer very little seismic energy into the ground.
- Atmospheric conditions like temperature inversions and calm surface winds can make sound propagate farther than normal.
- Aircraft actually produce two booms, but they usually arrive so close together that they’re indistinguishable from one another.
- USGS instruments are not designed to detect or analyze atmospheric phenomena, and atmospheric research is not part of the USGS mission.
- If you type “sonic boom” into our website search, you’ll get a listing of event pages for sonic booms, though it certainly isn’t comprehensive. Since these events are given a magnitude of 0.0, you will need to include ALL magnitudes in your Latest Earthquakes Map and List to see them.
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