M5.5 earthquake 5 km ESE of Asahi, Chiba, Japan
A magnitude 5.5 earthquake struck 5 km ESE of Asahi, Chiba, Japan at 00:07 local time (15:07 UTC) on 29 Oct 2026, at a depth of 41 km, according to USGS and GFZ.
Reported by 2 agencies · revised from M5.6
Data: USGS, GFZ · updated 2026-10-28 15:24 UTC · reviewed
- Magnitude
- 5.5moderate
moment magnitude (W phase) (mww)
revised from 5.6 - Depth
- 41.4 km
- Status
- Reviewed
- Origin time
- 2026-10-28 15:07:52 UTC
- Local: 29 Oct 2026, 00:07:52 (Asia/Tokyo)
- Epicentre
- 35.702° N, 140.706° E
Circles show this event and others within 71 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 |
|---|---|---|
| AsahiChiba, Japan · pop. 64,690 | 5 km | VModerate |
| ChoshiChiba, Japan · pop. 58,431 | 12 km | VModerate |
| HasakiChiba, Japan · pop. 39,209 | 12 km | VModerate |
| YōkaichibaChiba, Japan · pop. 32,651 | 14 km | VModerate |
| ChibaJapan · pop. 979,768 | 54 km | IVLight |
| IchiharaChiba, Japan · pop. 283,531 | 60 km | IVLight |
| KashiwaChiba, Japan · pop. 433,436 | 68 km | IVLight |
| MatsudoChiba, Japan · pop. 498,575 | 73 km | IVLight |
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 215 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.
How big was it?
Felt by most people over a wide area. Can damage poorly built structures close to the epicentre.
It released roughly the energy of 2.7 kt 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 41 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.
M5.5 releases about 32× the energy of M4.5, and its waves are about 10× taller on a seismogram. Energy: 2.7 kt of TNT vs 85 t of TNT.
Each square is the energy of one M4.5. Energy from log₁₀E = 1.5M + 4.8.
Aftershocks and nearby activity
No later earthquakes have been recorded within 71 km so far. 3 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.
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.
Event id gfz2026vdgw. First recorded here 28 Oct 2026, 15:20:07 UTC. Solutions: GFZ (geofon:gfz2026vdgw); USGS (usgs:us7000ttpe). Cite as: SeismoAtlas, “M5.5 earthquake 5 km ESE of Asahi, Chiba, Japan”, https://seismoatlas.com/earthquake/gfz2026vdgw-m5-5-earthquake-5-km-ese-of-asahi-chiba-japan, data from USGS, GFZ.
JSON: /api/v1/events/gfz2026vdgw. SeismoAtlas is not an official warning service.