M4.4 earthquake 10 km S of Choshi, Chiba, Japan
A magnitude 4.4 earthquake struck 10 km S of Choshi, Chiba, Japan at 17:27 local time (08:27 UTC) on 24 Sept 2026, at a depth of 52 km, according to USGS.
Data: USGS · updated 2026-10-07 12:12 UTC · reviewed
- Magnitude
- 4.4light
body-wave magnitude (mb) - Depth
- 51.5 km
- Status
- Reviewed
- Origin time
- 2026-09-24 08:27:27 UTC
- Local: 24 Sept 2026, 17:27:27 (Asia/Tokyo)
- Epicentre
- 35.638° N, 140.817° E
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Circles show this event and others within 30 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map
Nearby places
| Place | Distance | Est. shaking |
|---|---|---|
| ChoshiChiba, Japan · pop. 58,431 | 10 km | IIIWeak |
| HasakiChiba, Japan · pop. 39,209 | 10 km | IIIWeak |
| AsahiChiba, Japan · pop. 64,690 | 18 km | IIIWeak |
| YōkaichibaChiba, Japan · pop. 32,651 | 25 km | IIIWeak |
| ChibaJapan · pop. 979,768 | 63 km | IIWeak |
| IchiharaChiba, Japan · pop. 283,531 | 68 km | IIWeak |
| KashiwaChiba, Japan · pop. 433,436 | 79 km | IIWeak |
| MatsudoChiba, Japan · pop. 498,575 | 84 km | IIWeak |
Shaking is an estimate from the intensity prediction equation of Allen, Wald & Worden (2012), not an observation. Local ground and buildings can change it by a level or more. Likely felt out to about 42 km.
Every agency's solution
Agencies locate earthquakes with their own stations and methods, so their numbers differ. We match reports of the same event by time, distance and magnitude and show them side by side. The headline uses USGS, which has been reviewed by an analyst.
| Agency | Magnitude | Depth | Epicentre | Time offset | Status |
|---|---|---|---|---|---|
| USGSheadlineUSGS NEIC via U.S. Geological Survey | 4.4 mb | 51.5 km | 35.64° N, 140.82° E | – | Reviewed |
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How big was it?
Widely felt near the epicentre: rattling windows and objects. Significant damage is unlikely.
It released roughly the energy of 60 t of TNT. Magnitude is logarithmic: each whole step means about 32 times more energy and 10 times larger waves on a seismogram. Depth matters too: at 52 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.
M4.4 releases about 32× the energy of M3.4, and its waves are about 10× taller on a seismogram. Energy: 60 t of TNT vs 1.9 t of TNT.
Each square is the energy of one M3.4. Energy from log₁₀E = 1.5M + 4.8.
Aftershocks and nearby activity
9 later earthquakes within 30 km; the largest was M5.1 6 days ago. 1 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.
Mainshock M4.4
9 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).
| Time after mainshock (hours) | Magnitude | Depth (km) |
|---|---|---|
| 64.29 | 3.8 | 50 |
| 125.34 | 3.0 | 50 |
| 156.82 | 4.4 | 35 |
| 156.83 | 3.5 | 50 |
| 171.99 | 5.1 | 50 |
| 172.06 | 3.6 | 40 |
| 172.39 | 3.3 | 40 |
| 322.76 | 4.8 | 50 |
| 323.14 | 3.9 | 50 |
- 5.14 km SE of Sukayama, Chiba, Japan10-01 12:27
- 4.85 km ESE of Asahi, Chiba, Japan10-07 19:13
- 4.412 km SSE of Choshi, Chiba, Japan09-30 21:16
- 3.914 km SSE of Asahi, Chiba, Japan10-07 19:36
- 3.85 km ESE of Asahi, Chiba, Japan09-27 00:45
- 3.65 km ESE of Asahi, Chiba, Japan10-01 12:31
- 3.55 km E of Yōkaichiba, Chiba, Japan09-30 21:17
- 3.34 km SE of Sukayama, Chiba, Japan10-01 12:51
- 3.05 km E of Yōkaichiba, Chiba, Japan09-29 13:48
Did you feel it?
Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.
Reports on SeismoAtlas
No reports yet.
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Event id us6000tyv6. First recorded here 7 Oct 2026, 17:32:20 UTC. Solutions: USGS (usgs:us6000tyv6). Cite as: SeismoAtlas, “M4.4 earthquake 10 km S of Choshi, Chiba, Japan”, https://seismoatlas.com/earthquake/us6000tyv6-m4-4-earthquake-10-km-s-of-choshi-chiba-japan, data from USGS.
JSON: /api/v1/events/us6000tyv6. SeismoAtlas is not an official warning service.