Light mag. 4.0 earthquake - 52 mi southeast of Eureka, Humboldt County, California, USA, on Tuesday, 20 Apr 2021 2:48 am (GMT -7) -

Light mag. 4.0 earthquake - 52 mi southeast of Eureka, Humboldt County, California, USA, on Tuesday, 20 Apr 2021 2:48 am (GMT -7)

Light magnitude 4.0 earthquake at 34 km depth

20 Apr 09:51 UTC: First to report: USGS after 3 minutes.
20 Apr 09:53: Magnitude recalculated from 3.8 to 3.9.
20 Apr 10:44: Magnitude recalculated from 3.9 to 4.0.
20 Apr 18:22: Hypocenter depth recalculated from 31.2 to 33.9 km (from 19.4 to 21 mi).
Update Tue, 20 Apr 2021, 09:57
Small magnitude 3.9 earthquake 52 miles southeast of Eureka, California, United States
3.9 quake 20 Apr 2:48 am (GMT -7)
3.9 quake 20 Apr 2:48 am (GMT -7)
A moderately shallow magnitude 3.9 earthquake was reported early morning near Eureka, Humboldt County, California, USA.
According to the United States Geological Survey, the quake hit on Tuesday 20 April 2021 at 2:48 am local time at a moderately shallow depth of 19 miles. The exact magnitude, epicenter, and depth of the quake might be revised within the next few hours or minutes as seismologists review data and refine their calculations, or as other agencies issue their report.
Our monitoring service identified a second report from the European-Mediterranean Seismological Centre (EMSC) which listed the quake at magnitude 3.9 as well.
Towns or cities near the epicenter where the quake might have been felt as very weak shaking include Phillipsville (pop. 140) located 10 miles from the epicenter, Redway (pop. 1,200) 13 miles away, Rio Dell (pop. 3,400) 34 miles away, Fortuna (pop. 12,000) 41 miles away, Bayside (pop. 17,100) 51 miles away, Eureka (pop. 27,000) 52 miles away, and Arcata (pop. 17,800) 53 miles away. In McKinleyville (pop. 15,200, 59 miles away), the quake was probably not felt.
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Earthquake data:

Date & time: 20 Apr 2021 09:48:34 UTC -
Local time at epicenter: Tuesday, 20 Apr 2021 2:48 am (GMT -7)
Magnitude: 4
Depth: 33.9 km
Epicenter latitude / longitude: 40.188°N / 123.59883°W (Humboldt, California, United States)
Nearest volcano: Clear Lake (153 km / 95 mi)
Nearby towns and cities:
16 km (10 mi) E of Phillipsville (pop: 140) --> See nearby quakes!
21 km (13 mi) ENE of Redway (pop: 1,230) --> See nearby quakes!
55 km (34 mi) SE of Rio Dell (pop: 3,390) --> See nearby quakes!
66 km (41 mi) SE of Fortuna (Humboldt County) (pop: 12,000) --> See nearby quakes!
83 km (51 mi) SSE of Bayside (Humboldt County) (pop: 17,100) --> See nearby quakes!
83 km (52 mi) SE of Eureka (Humboldt County) (pop: 27,000) --> See nearby quakes!
86 km (53 mi) SSE of Arcata (Humboldt County) (pop: 17,800) --> See nearby quakes!
94 km (59 mi) SSE of McKinleyville (Humboldt County) (pop: 15,200) --> See nearby quakes!
209 km (130 mi) NNW of Santa Rosa (pop: 175,000) --> See nearby quakes!
254 km (158 mi) NW of Sacramento (pop: 490,700) --> See nearby quakes!
Weather at epicenter at time of quake:
Broken Clouds 10°C (50 F), humidity: 68%, wind: 0 m/s (1 kts)
Primary data source: USGS (United States Geological Survey)
Estimated released energy: 6.3 x 1010 joules (17.5 megawatt hours, equivalent to 15.1 tons of TNT) More info
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Data for the same earthquake reported by different agencies

Info: The more agencies report about the same quake and post similar data, the more confidence you can have in the data. It takes normally up to a few hours until earthquake parameters are calculated with near-optimum precision.
MagnitudeDepthLocationSource
4.034 km20km ENE of Redway, CA, USAUSGS
unspecifiedn/aNear Redway, California, USAVolcanoDiscovery
3.934 kmNORTHERN CALIFORNIA, USAEMSC

User reports for this quake (12)

User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
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Garberville CA / Weak shaking (MMI III) / complex motion difficult to describe / 1-2 s : My adrenaline spiked as my second story room sounded bassy and shook. At onset I felt my sense of gravity become muddied like I was in an elevator. | 7 users found this interesting.  
Adelanto / Light shaking (MMI IV) / horizontal (sideways) swinging / 5-10 s : I was having trouble sleeping around 2am to 230am. Eventually I fell asleep but had a dream I was in an earthquake with noticeable horizontal swaying for several seconds. I woke up and felt small sways but couldn't tell. I checked this site and only earthquake near that time was this one but I am in Adelanto in Southern California. | 8 users found this interesting.  
Palmdale (788.6 km SE of epicenter) [Map] / Light shaking (MMI IV) / 1-2 s : Felt a quick shake up and down enough to shake my fishbowl next to me | 4 users found this interesting.  
Garberville / Light shaking (MMI IV) / horizontal (sideways) swinging / 1-2 s : Like some diety smacked the side of the house with the back of their hand. | 4 users found this interesting.  
  • I think The Universe is trying to Say something. Mother Earth isn’t very happy with Her Children. Stay grounded and breathing, blessings to all
20.7 km SW of epicenter [Map] / Very weak shaking (MMI II) : East to west shimmy .8 | 3 users found this interesting.  
Suisun / Weak shaking (MMI III) / 5-10 s : Bed post shaking, was not sure if it was caused by passing train or not | One user found this interesting.  
Garberville, CA / Weak shaking (MMI III) / rattling, vibrating / 2-5 s
254.7 km SE of epicenter [Map] / not felt (reported through our app)
West sacramento ca (250.9 km SE of epicenter) [Map] / not felt (reported through our app)
Garberville, CA (36.6 km WSW of epicenter) [Map] / Light shaking (MMI IV) / single vertical bump / 1-2 s : Woke me. Unmistakable short shake  
272.4 km SSE of epicenter [Map] / not felt (reported through our app)
272.3 km SSE of epicenter [Map] / not felt (reported through our app)
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