It is assumed that this record was not from an actual earthquake. It could be due to another (unknown) event causing the shock, such as B. Weather and sonic booms. In other cases, officially reported quakes are sometimes removed later.
This can happen when initial automatic calculations return an earthquake, but turn out to be incorrect in subsequent (manual) revision.
The first report is below:
Our surveillance service AllQuakes received reports of an earthquake in or near San Francisco, California, USA at around 7:53 AM GMT. Unless at least one national or international seismological agency confirms this, their status remains unconfirmed.
20 Apr 07:56 UTC: First report: VolcanoDiscovery after 3 minutes.
I felt this tremor
I didn’t feel it
Date and time: April 20, 2021 07:53:57 UTC –
Depth: 10.0 km
Latitude / Longitude of epicenter: 37.81467 ° N / 122.27234 ° W. (California, USA)
Nearest volcano: Clear Lake (136 km)
Primary data source: VolcanoDiscovery
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Data for the same earthquake reported by different authorities
Info: The more agencies report on the same quake and publish similar data, the more confidence you can have in the data. It usually takes up to a few hours for the earthquake parameters to be calculated with near optimal accuracy.
User reports for this quake (2)
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Oakland / slight shaking (MMI IV) / single vertical bump / very brief
Oakland ca (0 km southeast of the epicenter) [Map] / Very weak shaking (MMI II) / 1-2 s : Felt my house tremble for two seconds
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