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Moderate mag. 3.9 earthquake - 24 mi north of Santa Rosa, Sonoma County, California, on Wednesday, August 12, 2020 at 11:45 GMT

Moderate mag. 3.9 earthquake - 24 mi north of Santa Rosa, Sonoma County, California, on Wednesday, August 12, 2020 at 11:45 GMT Moderate mag. 3.9 earthquake - 24 mi north of Santa Rosa, Sonoma County, California, on Wednesday, August 12, 2020 at 11:45 GMT

Moderate magnitude 3.9 earthquake at 4 km depth

12 Aug 11:46 UTC: First to report: USGS after 59 seconds.
Aug 12 11:49: Magnitude recalculated from 4.1 to 4.0.
Hypocenter depth recalculated from 8.0 to 4.1 km.
Aug 12 11:51: Magnitude recalculated from 4.0 to 3.9.

Earthquake details

Date & timeAug 12, 2020 11:45:43 UTC
Local time at epicenter
Depth4.1 km
Epicenter latitude / longitude38.78667°N / 122.74917°W (Lake, California, United States)
Antipode38.787°S / 57.251°E
Shaking intensityWeak shaking
Felt3 reports
Primary data sourceUSGS (United States Geological Survey)
Nearest volcanoClear Lake (21 km / 13 mi)
Nearby towns and cities5 km (3 mi) SSW of Cobb (pop: 1,780) | Show on map | Quakes nearby
17 km (10 mi) W of Hidden Valley Lake (pop: 5,580) | Show on map | Quakes nearby
22 km (14 mi) SSW of Clearlake (Lake County) (pop: 15,200) | Show on map | Quakes nearby
22 km (14 mi) NNE of Russian River (Sonoma County) (pop: 11,700) | Show on map | Quakes nearby
22 km (14 mi) NNE of Russian River (pop: 11,700) | Show on map | Quakes nearby
27 km (17 mi) NNE of Windsor (Sonoma County) (pop: 27,500) | Show on map | Quakes nearby
39 km (24 mi) N of Santa Rosa (pop: 175,000) | Show on map | Quakes nearby
50 km (31 mi) N of Rohnert Park (pop: 42,400) | Show on map | Quakes nearby
68 km (42 mi) NW of Napa (pop: 80,400) | Show on map | Quakes nearby
111 km (69 mi) WNW of Sacramento (pop: 490,700) | Show on map | Quakes nearby
Estimated seismic energy released4.5 x 1010 joules (12.4 megawatt hours, equivalent to 10.7 tons of TNT) | about seismic energy
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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.
3.94.1 km1km NNE of The Geysers, CA (USA)USGS
3.94 kmNorthern California (USA)EMSC

User reports for this quake (10)

User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
Leave a comment if you find a particular report interesting or want to add to it.
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Send your own user report!
5655 Saint Helena Road, Santa Rosa CA / Weak shaking (MMI III) : I did not feel a "shaking" at all, but only one powerful jerk/thrust.  
cobb / Light shaking (MMI IV) : woke me up  
Santa Rosa, CA / Very weak shaking (MMI II)
Noe Valley (United States, 119 km S of epicenter) : Just a light jiggle in SF (reported through EMSC)  
Lower Lake (United States, 18 km NE of epicenter) : I FELT A LITTLE SHAKE IN OUR TRAILER...I THOUGHT IT WAS A TREMOR AT THE TIME... (reported through EMSC)  
San Francisco (United States of America, 114 km S of epicenter) : Mild shake, 5 seconds long. (reported through EMSC)  
Ross (United States, 91 km S of epicenter) : Was sound asleep but a small shake plus rattling sound woke me up. (reported through EMSC)  
Suisun (United States, 87 km SE of epicenter) : Was in the tub, not sure if I was feeling a shake, but looked up to see toner sloshing in bottle a little. No reaction from Chihuahuas and cat. (reported through EMSC)  
Napa (United States, 67 km SE of epicenter) : Minor back and forth for less than 5 seconds. In bed, St. Helena. (reported through EMSC)  
Santa Rosa (United States of America, 36 km S of epicenter) : I was awake but lying down. Sharp jolt felt from North, wall mounted shelves on brackets made cracking sound as jolt felt. Slight swaying motion to room briefly upon standing. (reported through EMSC)  
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