Moderate mag. 5.2 earthquake - North Pacific Ocean, 127 km east of Mito, Ibaraki, Japan, on Wednesday, Aug 4, 2021 5:43 am (GMT +9) -

This quake was likely an aftershock of the 5.8 quake North Pacific Ocean, 98 km northeast of Hasaki, Chōshi-shi, Chiba, Japan, Aug 4, 2021 5:33 am (GMT +9), which had occurred 10 minutes earlier.
Moderate mag. 5.2 earthquake - North Pacific Ocean, 127 km east of Mito, Ibaraki, Japan, on Wednesday, Aug 4, 2021 5:43 am (GMT +9)

Moderate magnitude 5.2 earthquake at 30 km depth

3 Aug 20:44 UTC: First to report: VolcanoDiscovery after 1 minute.
3 Aug 20:53: Now using data updates from GFZ
3 Aug 20:55: Epicenter location corrected by 5.4 km (3.3 mi) towards W.
3 Aug 21:04: Magnitude recalculated from 5.5 to 5.2. Hypocenter depth recalculated from 10.0 to 30.0 km (from 6.2 to 18.6 mi). Epicenter location corrected by 12 km (7.3 mi) towards W.
Update Tue, 3 Aug 2021, 21:00
Significant magnitude 5.5 quake hits 119 km northeast of Hasaki, Japan early morning
5.5 quake 4 Aug 5:43 am (GMT +9)
5.5 quake 4 Aug 5:43 am (GMT +9)
A magnitude 5.5 earthquake near Hasaki, Chōshi-shi, Chiba, Japan, was reported only 17 minutes ago by the German Research Centre for Geosciences (GFZ), considered one of the key international agencies that monitor seismic activity worldwide. The earthquake occurred at a shallow depth of 10 km beneath the epicenter early morning on Wednesday 4 August 2021 at 5:43 am local time. 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 France's Réseau National de Surveillance Sismique (RéNaSS) which listed the quake at magnitude 5.6. A third agency, the European-Mediterranean Seismological Centre (EMSC), reported the same quake at magnitude 5.5.
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 Hasaki (pop. 39,200) located 119 km from the epicenter, Kashima-shi (pop. 65,800) 125 km away, Hitachi (pop. 186,300) 126 km away, Katsuta (pop. 156,000) 131 km away, Hitachi-Naka (pop. 156,800) 131 km away, and Iwaki (pop. 357,300) 132 km 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.
Download the Volcanoes & Earthquakes app and get one of the fastest seismic alerts online:
Android | iOS

Earthquake data

Date & time: Aug 3, 2021 20:43:15 UTC -
Local time at epicenter: Wednesday, Aug 4, 2021 5:43 am (GMT +9)
Magnitude: 5.2
Depth: 30.0 km
Epicenter latitude / longitude: 36.27°N / 141.86°E (North Pacific Ocean, Japan)
Antipode: 36.27°S / 38.14°W
Nearest volcano: Hakone (96 km / 60 mi)
Nearby towns and cities:
110 km (68 mi) NE of Hasaki (pop: 39,200) --> See nearby quakes!
114 km (71 mi) ENE of Kashima-shi (pop: 65,800) --> See nearby quakes!
114 km (71 mi) ESE of Hitachi (pop: 186,300) --> See nearby quakes!
120 km (74 mi) E of Katsuta (pop: 156,000) --> See nearby quakes!
120 km (74 mi) E of Hitachi-Naka (pop: 156,800) --> See nearby quakes!
123 km (76 mi) SE of Iwaki (pop: 357,300) --> See nearby quakes!
127 km (79 mi) E of Mito (pop: 246,500) --> See nearby quakes!
129 km (80 mi) ENE of Katori-shi (pop: 83,200) --> See nearby quakes!
206 km (128 mi) ENE of Tokyo (pop: 8,336,600) --> See nearby quakes!
220 km (137 mi) ENE of Yokohama (pop: 3,574,400) --> See nearby quakes!
348 km (216 mi) E of Honshū Island (pop: 104,000,000) --> See nearby quakes!
323 km (201 mi) NE of Shikine-jima Island (pop: 600) --> See nearby quakes!
Weather at epicenter at time of quake:
Clear Sky 26.4°C (80 F), humidity: 87%, wind: 5 m/s (9 kts) from SSW
Primary data source: GFZ (German Research Centre for Geosciences)
Estimated released energy: 4 x 1012 joules (1.11 gigawatt hours, equivalent to 951 tons of TNT) More info
Show interactive Map
[smaller] [bigger]
If you felt this quake (or if you were near the epicenter), please share your experience and submit a short "I felt it" report! Other users would love to hear about it!
If you did NOT feel the quake although you were in the area, please report it! Your contribution is valuable to earthquake science, seismic hazard analysis and mitigation efforts. You can use your device location or the map to indicate where you were during the earthquake. Thank you!

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.
5.230 kmOff East Coast of Honshu, JapanGFZ
5.410 kmJapan: Near TokyoRENASS
4.710 km114 Km ENE of Hasaki, JapanUSGS
5.339 kmNear East Coast of Honshu, JapanGeoAu
5.410 kmNear East Coast of Honshu, JapanBMKG

User reports for this quake (6)

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.
Flag as inappropriate.
Mark as helpful or interesting.
Send your own user report!
Narita, Chiba (148.2 km WSW of epicenter) [Map] / Very weak shaking (MMI II) / horizontal (sideways) swinging / 10-15 s
Kōriyama, Fukushima (181.1 km NW of epicenter) [Map] / Weak shaking (MMI III) / 2-5 s
Chiba (174.9 km WSW of epicenter) [Map] / Light shaking (MMI IV) : Swaying now and 5 minutes ago  
Shiki, Saitama (210.9 km WSW of epicenter) [Map] / Very weak shaking (MMI II) / several minutes : Small shakes, seconds to minutes apart. Felt on second floor. Still happening.  
Funabashi / Weak shaking (MMI III)
Sendai-shi (239.6 km NNW of epicenter) [Map] / Weak shaking (MMI III) / 15-20 s
Volcanoes & Earthquakes - new app for Android

Earlier earthquakes in the same area

Try our free app!
Volcanoes & Earthquakes - new app for Android
Android | iOS version
Why is there advertising on this site?
Support us - Help us upgrade our services!
We truly love working to bring you the latest volcano and earthquake data from around the world. Maintaining our website and our free apps does require, however, considerable time and resources.
We need financing to increase hard- and software capacity as well as support our editor team. We're aiming to achieve uninterrupted service wherever an earthquake or volcano eruption unfolds, and your donations can make it happen! Every donation will be highly appreciated. If you find the information useful and would like to support our team in integrating further features, write great content, and in upgrading our soft- and hardware, please make a donation (PayPal or Online credit card payment).

Planned features:
  • Improved multilanguage support
  • Tsunami alerts
  • Faster responsiveness
Thanks to your past donations, these features have been added recently:
  • Earthquake archive from 1900 onwards
  • Detailed quake stats
  • Additional seismic data sources
Download and Upgrade the Volcanoes & Earthquakes app to get one of the fastest seismic and volcano alerts online:
Android | IOS
Thank you!
Copyrights: VolcanoDiscovery and other sources as noted.
Use of material: Most texts and images, in particular photographs, on this website are protected by copyright. Further reproduction and use of without authorization is usually not consented. If you are not sure or need licensing rights for photographs, for example for publications and commercial use, please contact us.