0 km NNE of Yōkaichiba, Japan

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 11 people have reported feeling it to USGS.

How big was it?

This earthquake released about 1.3 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.3 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 130× the energy of this one
2. Mineral, Virginia 2011 M 5.8 5.6× the energy of this one
3. Magna, Utah 2020 M 5.7 4× the energy of this one
4. This earthquake M 5.3 about 1.3 kilotons of TNT
5. Around the size people start to feel M 3.0 this one released 2,800× more

Energy from the Gutenberg–Richter relation (log₁₀E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.

For this area

The largest earthquake within 50 km in our catalogue was M 4.4 on 2026-09-30.

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 35.7025, 140.5507. Map © OpenStreetMap contributors.

Aftershocks so far

No further earthquakes have been recorded within 50 km since this one.

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 14:08 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

Revisions

USGS refines a solution as more stations report. Every change we have seen is listed here.

On USGS

• The official USGS event page — the source of record for every value above
• Did you feel it? Report it to USGS — reports go to USGS, not to us
• ShakeMap for this event, when USGS has produced one

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.