Light magnitude 4.3 earthquake at 49 km depth
12 Aug 06:16 UTC: First to report: VolcanoDiscovery after 3 minutes.
12 Aug 06:17: Now using data updates from EMSC
12 Aug 06:39: Hypocenter depth recalculated from 36.8 to 49.4 km (from 23 to 31 mi). Epicenter location corrected by 3 km (1.9 mi) towards SSW.
Update Thu, 12 Aug 2021, 06:27
Moderate earthquake of magnitude 4.3 just reported 51 miles northwest of Alaska City, Alaska, United States
4.3 quake 11 Aug 10:13 pm (GMT -8)
The United States Geological Survey reported a magnitude 4.3 quake in the United States near Alaska City, Anchorage, Alaska, only 13 minutes ago. The earthquake hit late at night on Wednesday 11 August 2021 at 10:13 pm local time at a moderately shallow depth of 23 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 4.3 as well.
Based on the preliminary seismic data, the quake should not have caused any significant damage, but was probably felt by many people as light vibration in the area of the epicenter.
Weak shaking might have been felt in Willow (pop. 2,100) located 19 miles from the epicenter.
Other towns or cities near the epicenter where the quake might have been felt as very weak shaking include Houston (pop. 2,200) located 29 miles from the epicenter, Meadow Lakes (pop. 7,600) 35 miles away, Knik-Fairview (pop. 14,900) 40 miles away, Tanaina (pop. 8,200) 40 miles away, Wasilla (pop. 9,300) 41 miles away, Eagle River (pop. 24,800) 50 miles away, Eagle River (pop. 24,800) 50 miles away, and Alaska City (pop. 298,700) 51 miles away.
VolcanoDiscovery will automatically update magnitude and depth if these change and follow up if other significant news about the quake become available. If you’re in the area, please send us your experience through our reporting mechanism, either online or via our mobile app. This will help us provide more first-hand updates to anyone around the globe who wants to know more about this quake.
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Earthquake data
Date & time: Aug 12, 2021 06:13:59 UTC –
Local time at epicenter: Wednesday, Aug 11, 2021 at 10:13 pm (GMT -8)
Magnitude: 4.3
Depth: 49.4 km
Epicenter latitude / longitude: 61.8658°N / 150.5399°W 
(Matanuska-Susitna, Alaska, United States)
Antipode: 61.866°S / 29.46°E
Nearest volcano: Hayes (105 km / 65 mi)
Nearby towns and cities:
30 km (18 mi) WNW of Willow Creek (pop: 2,100) –> See nearby quakes!
46 km (29 mi) NW of Houston (pop: 2,210) –> See nearby quakes!
49 km (30 mi) SW of Susitna North (pop: 1,260) –> See nearby quakes!
49 km (31 mi) NW of Big Lake (pop: 3,350) –> See nearby quakes!
56 km (35 mi) WNW of Meadow Lakes (pop: 7,570) –> See nearby quakes!
63 km (39 mi) NW of Knik-Fairview (pop: 14,900) –> See nearby quakes!
70 km (43 mi) W of Fishhook (pop: 4,680) –> See nearby quakes!
79 km (49 mi) NW of Eagle River (pop: 24,800) –> See nearby quakes!
79 km (49 mi) NW of Eagle River (Anchorage) (pop: 24,800) –> See nearby quakes!
80 km (49 mi) NNW of Alaska City (pop: 298,700) –> See nearby quakes!
Weather at epicenter at time of quake:
Light Rain 
11.8°C (53 F), humidity: 98%, wind: 2 m/s (4 kts) from N
Primary data source: USGS (United States Geological Survey)
Estimated released energy: 1.8 x 1011 joules (49.4 megawatt hours, equivalent to 42.5 tons of TNT) | about seismic energy
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.
| Mag. | Depth | Location | Source |
| 4.3 | 49 km | 29 Km WNW of Willow, Alaska | USGS |
| 4.2 | 61 km | SOUTHERN ALASKA | EMSC |
User reports for this quake (37)
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near Bear Creek, Kenai Peninsula, Alaska (180.1 km SSE of epicenter) [Map] / Weak shaking (MMI III) / rattling, vibrating / 10-15 s : Moose Pass, AK Inside 40’ motorhome. Felt extended period of shaking despite having four hydraulic stabilizers deployed and all 6 tires on the ground. Commented to each other, “Oh, there’s another earthquake & it’s lasting awhile. Wonder where it | 3 users found this interesting.
Wasilla Meadowlands area (62.8 km ESE of epicenter) [Map] / Weak shaking (MMI III) / rattling, vibrating / 5-10 s : Dog and cat heardnitnfirst then small shaking that kept on going ever so slightly | 2 users found this interesting. (reported through our app)
JBER, AK / Weak shaking (MMI III) / single vertical bump / very short : All we felt was a single bump, shook our furniture. | 2 users found this interesting.
Anchorage (92.6 km SSE of epicenter) [Map] / Weak shaking (MMI III) / rattling, vibrating / 5-10 s : Wasn’t sure it was even an earthquake (just moved into our new house) looked outside and the wind was blowing hard so figured it was just a strong gust. I was at the kitchen table on my surface and felt just the slightest movement, no one else in the hous | One user found this interesting. (reported through our app)
Anchorage international airport / Very weak shaking (MMI II) / very short : Shaking while sitting on the floor of the upper level of airport terminal. My husband felt it too. | One user found this interesting.
East anchorage (87.2 km SSE of epicenter) [Map] / Light shaking (MMI IV) / single lateral shake / 1-2 s : Like a few shoves to the building in sucsetion was able to more lateral feeling no aftershocks felt yet 10:36 | One user found this interesting.
Eagle River / Weak shaking (MMI III) / single lateral shake / 2-5 s : It was a gentle roll back and forth. | One user found this interesting.
eagle river alaska / Very weak shaking (MMI II) / rattling, vibrating / 1-2 s : very short felt by dogs. | One user found this interesting.
Anchorage / Weak shaking (MMI III) / single vertical bump / very short : Slight shake | One user found this interesting.
Eagle River, Anchorage, Alaska (78.4 km SE of epicenter) [Map] / Very weak shaking (MMI II) / rattling, vibrating / 5-10 s (reported through our app)
Elmendorf Air Force Base, Anchorage County, Alaska (81.9 km SE of epicenter) [Map] / Weak shaking (MMI III) / 1-2 s : Just a quick little shimmy shimmy after getting into bed. Not the shimmy shimmy I was hoping for.
Meadow Lakes, Matanuska-Susitna, Alaska (54.6 km ESE of epicenter) [Map] / Very weak shaking (MMI II) / single lateral shake / very short
Alaska City, Anchorage (81.3 km SSE of epicenter) [Map] / Very weak shaking (MMI II) / single lateral shake / very short
Alaska City, Anchorage (81.6 km SSE of epicenter) [Map] / Very weak shaking (MMI II)
Alaska City, Anchorage (83.2 km SSE of epicenter) [Map] / Very weak shaking (MMI II) / horizontal (sideways) swinging / 1-2 s (reported through our app)
Knik-Fairview, Matanuska-Susitna, Alaska (63.1 km SE of epicenter) [Map] / Light shaking (MMI IV) / horizontal (sideways) swinging / 2-5 s (reported through our app)
Alaska City, Anchorage (84.1 km SSE of epicenter) [Map] / Very weak shaking (MMI II) / rattling, vibrating / 5-10 s (reported through our app)
Alaska City, Anchorage (84.1 km SSE of epicenter) [Map] / Weak shaking (MMI III) (reported through our app)
Lakes, Matanuska-Susitna, Alaska (69.6 km ESE of epicenter) [Map] / Very weak shaking (MMI II) / rattling, vibrating / 1-2 s (reported through our app)
Anchorage, AK (91.5 km SSE of epicenter) [Map] / Very weak shaking (MMI II) / rattling, vibrating / 1-2 s
anchorage, ak / Very weak shaking (MMI II) / 20-30 s
anchorage, ak / Very weak shaking (MMI II) / 20-30 s
Anchorage (5.1 km NE of epicenter) [Map] / Light shaking (MMI IV) / very short
Anchorage, AK (80.9 km SSE of epicenter) [Map] / Light shaking (MMI IV) / horizontal (sideways) swinging / 5-10 s : Lying in bed, single vertical jump then horizontal swaying. Live on third floor of an apartment building.
Anchorage (5.1 km NE of epicenter) [Map] / Light shaking (MMI IV) / very short
Anchorage (83 km SSE of epicenter) [Map] / Weak shaking (MMI III) / rattling, vibrating / 2-5 s
Girdwood (125.7 km SE of epicenter) [Map] / Light shaking (MMI IV) / single vertical bump / 2-5 s (reported through our app)
Anchorage, al 99504 (85.4 km SSE of epicenter) [Map] / Light shaking (MMI IV) / complex motion difficult to describe / 30-60 s
Anchorage, Alaska (92.7 km SSE of epicenter) [Map] / Very weak shaking (MMI II) / single lateral shake / 5-10 s (reported through our app)
Eagle river / Very weak shaking (MMI II) / rattling, vibrating / 5-10 s
Anchorage (91.1 km SSE of epicenter) [Map] / Weak shaking (MMI III) / rattling, vibrating / 1-2 s (reported through our app)
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