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 6:44 am GMT. Unless at least one national or international seismological agency confirms this, their status remains unconfirmed.
20 Apr 06:47 UTC: First report: VolcanoDiscovery after 3 minutes.
I felt this tremor
I didn’t feel it
Date and time: April 20, 2021 06:44:32 UTC –
Depth: 10.0 km
Latitude / Longitude of epicenter: 37.75952 ° N / 122.421 ° W. (California, USA)
Nearest volcano: Clear Lake (138 km)
Primary data source: VolcanoDiscovery
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Data for the same earthquake reported by different authorities
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User reports for this quake (2)
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San Francisco, CA (0 km ESE of epicenter) [Map] / Very weak shaking (MMI II) / rattling, vibrating / 1-2 s
Santa Clara / weak shaking (MMI III) / both vertical and horizontal swing / 20-30 s : Body swayed on the couch in my house
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