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M4.8 earthquake near Tsukuba, Ibaraki, Japan

A magnitude 4.8 earthquake struck near Tsukuba, Ibaraki, Japan at 00:07 local time (15:07 UTC) on 17 Sept 2026, at a depth of 70 km, according to JMA and USGS. The solution is preliminary and may be revised.

Reported by 2 agencies · 73 reports to USGS “Did You Feel It?”

Data: JMA, USGS · updated 2026-09-23 18:16 UTC · automatic solution

Magnitude
4.8light
JMA magnitude (Mj)
Depth
70 km
Status
Automatic
Origin time
2026-09-16 15:07:00 UTC
Local: 17 Sept 2026, 00:07:00 (Asia/Tokyo)
Epicentre
36.100° N, 140.100° E

Circles show this event and others within 32 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map

Nearby places

Distance and estimated shaking at nearby places
PlaceDistanceEst. shaking
TsukubaIbaraki, Japan · pop. 241,6563 kmIIIWeak
NakaIbaraki, Japan · pop. 53,1378 kmIIIWeak
TsuchiuraIbaraki, Japan · pop. 144,39910 kmIIIWeak
IshigeIbaraki, Japan · pop. 24,94812 kmIIIWeak
KashiwaChiba, Japan · pop. 433,43629 kmIIIWeak
KoshigayaSaitama, Japan · pop. 345,35336 kmIIIWeak
MatsudoChiba, Japan · pop. 498,57540 kmIIIWeak
MitoIbaraki, Japan · pop. 270,68542 kmIIIWeak

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 75 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 JMA.

AgencyMagnitudeDepthEpicentreTime offsetStatus
JMAheadlineJMA via Japan Meteorological Agency4.8 Mj70 km36.10° N, 140.10° E–Automatic
USGSUSGS NEIC via U.S. Geological Survey4.8 mww80.9 km36.15° N, 140.07° E+38.8 sReviewed

How big was it?

Widely felt near the epicentre: rattling windows and objects. Significant damage is unlikely.

It released roughly the energy of 239 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 70 km this was a intermediate-depth earthquake, which spreads shaking over a wider area but less intensely.

M4.8 releases about 32× the energy of M3.8, and its waves are about 10× taller on a seismogram. Energy: 239 t of TNT vs 7.6 t of TNT.

Each square is the energy of one M3.8. Energy from log₁₀E = 1.5M + 4.8.

Aftershocks and nearby activity

3 later earthquakes within 32 km; the largest was M4.9 46 min ago. Aftershock rates usually fall off roughly in proportion to 1/time.

Aftershocks

Mainshock M4.8

3 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).

Aftershocks
Time after mainshock (hours)MagnitudeDepth (km)
6.073.150
135.453.950
292.634.950
  1. 4.94 km NE of Bandō, Ibaraki, Japan09-28 19:45
  2. 3.93 km NE of Shimo-tsuma, Ibaraki, Japan09-22 06:34
  3. 3.14 km NE of Bandō, Ibaraki, Japan09-16 21:11

Did you feel it?

Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.

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Reports on SeismoAtlas

No reports yet.

USGS “Did You Feel It?” has 73 reports: add yours at USGS.

Event id jma20260917000748. First recorded here 28 Sept 2026, 17:32:06 UTC. Solutions: JMA (jma:20260917000748); USGS (usgs:us7000thv6). Cite as: SeismoAtlas, “M4.8 earthquake near Tsukuba, Ibaraki, Japan”, https://seismoatlas.com/earthquake/jma20260917000748-m4-8-earthquake-near-tsukuba-ibaraki-japan, data from JMA, USGS.

JSON: /api/v1/events/jma20260917000748. SeismoAtlas is not an official warning service.