TOKYO — A magnitude 6.0 earthquake was registered at 22:15 UTC on Saturday, October 31, approximately 58 km (36 miles) south-southeast of Shima, Japan, at a depth of 352.4 km, as reported by the US Geological Survey (USGS). The epicentre was at 33.8°N, 137.0°E, near Shima, a city on the southeastern coast of Honshu, and the USGS issued a green alert for the event, indicating a low likelihood of casualties and damage.

Source: Watchers, reporting USGS data, October 31, 2026

The European-Mediterranean Seismological Centre (EMSC) independently measured the same event at magnitude 6, at a depth of 352 km near the south coast of Honshu, according to EMSC data reported on Saturday evening. Early readings from different agencies can differ slightly as seismologists revise their solutions; here the two agencies agreed on both the magnitude and the depth.

Source: EMSC data via Breaking The News / BizToc, October 31, 2026

6.0Magnitude (mww) recorded by the USGS; EMSC also measured 6.0
352.4 kmDepth — a deep-focus quake, which is why so little was felt at the surface
22:15 UTCOrigin time Saturday — 7:15 a.m. Sunday in Japan, 6:15 p.m. Saturday in Toronto
IIIMaximum estimated shaking intensity; only about a dozen felt reports reached the USGS

Why so little shaking at the surface

This was a deep-focus earthquake: with the rupture hundreds of kilometres down, the shaking spreads widely but is weaker by the time it reaches the surface. Monitoring based on USGS data put the maximum estimated intensity at III on the Modified Mercalli scale, with a significance index of 554, and only about a dozen people had reported feeling it to the USGS. No casualties or damage had been reported in the agency data available when this story was published.

Source: Zenit, reporting USGS data, October 31, 2026

There is no tsunami threat associated with this earthquake, based on its location and available data — a deep rupture of this kind does not displace the seafloor the way a shallow undersea quake can, and neither the USGS nor the Pacific Tsunami Warning Center issued any warning, watch or advisory for the event.

Source: Earthquake Today, reporting USGS telemetry for event us7000tuku, October 31, 2026

The epicentre lies off Japan's Pacific coast, south of Honshu, in one of the world's most closely watched seismic zones, where the Philippine Sea plate dives beneath Japan along the Nankai Trough. Saturday's quake, however, was far below that plate boundary, in the deep zone where such events are recorded several times a year around Japan and rarely cause harm. Seismologists may still revise the figures as more station data is reviewed.