Quake information: Reported (unconfirmed) earthquake: 0.5 mi southwest of San Francisco, California, USA, 27 April 2021 07:56 GMT

April 27, 2021

0 0 2 minutes read

It is assumed that this record was not from an actual earthquake. This may be due to some other (unknown) event that causes tremors, e.g. B. Explosions, sonic booms, weather or other human or natural causes. Even officially reported earthquakes are sometimes removed again later when seismic signals that were initially processed automatically are later manually reinterpreted so that they do not originate from real earthquakes.

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 7:56 GMT. Unless at least one national or international seismological agency confirms this, their status remains unconfirmed.

27 Apr 08:04 UTC: First report: VolcanoDiscovery after 8 minutes.

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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.

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User reports for this quake (2)

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Visalia, ca / weak shaking (MMI III) / complex movement difficult to describe / very brief : Slight jerk. Almost like I’m dizzy. But the brand new detergent tub fell off the counter and burst all over the floor.

San Francisco 94109 (0 km northeast of the epicenter) [Map] / Very weak shaking (MMI II) / rattling, vibrating / very briefly : One of those times you can’t tell if it’s a quake – but dogs barked

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