At 15:07 GMT on October 29, a 5.4‑magnitude earthquake jolted the north‑east coast of Honshu, Japan, according to a report from the German Research Centre for Geosciences (GFZ). The GFZ identified the quake’s epicenter at 35.67° N, 140.59° E, with a depth of 49.4 km. The event shook a coastal region of Chiba Prefecture near Tokyo and was classified as code B (lower 5) on Japan’s seismic intensity scale.
Japan’s Meteorological Agency (JMA) issued an automated alert shortly after the quake, stating a preliminary magnitude of 5.4 and a depth of 50 km. The alert confirmed that the earthquake posed no tsunami threat. The JMA’s alerts indicated that shaking was registered in Chiba, Tokyo, and neighbouring prefectures such as Tochigi, Ibaraki and Saitama.
A separate Kyodo News report, published later on October 29, described the same event as a preliminary 5.5‑magnitude quake. The report noted that the JMA had initially catalogued the magnitude as 5.4 but later revised it to 5.5 as more data became available. In that account, the quake’s depth was reported as roughly 52 km, and the intensity was again recorded as lower 5, with no tsunami concerns.
Earlier brief releases from the JMA emphasized that the crustal movement was moderate and confined to the near‑surface layers. The agency’s seismic intensity map showed maximum shakiness in Yokoshibahikari where a lower 5 reading was documented, while the rest of the prefecture experienced weaker vibrations. The event was not strong enough to trigger any emergency measures.
The GFZ, which worked with the Chinese satellite-based monitoring system, selected a slightly different epicenter latitude and longitude from the JMA’s reporting. While the GFZ’s coordinates placed the focus 0.03° to the south of the JMA’s, both agencies agreed on a depth near 50 km and the absence of a tsunami. The difference in depth measurements is within typical uncertainties for offshore events.
Kyodo News’s digest for Oct. 29, 2026 also lists the quake as a 5.5 magnitude event, citing the JMA’s updated figures. The digest mentions that early alerts had used 5.4 and that the magnitude was subsequently revised after additional calculations. No discrepancies exist in terms of the quake’s surface reach or impact on infrastructure.
Uncertainties remain regarding the final magnitude and exact depth of the earthquake, as two reputable agencies report 5.4 and 5.5 magnitudes and depth estimates ranging from 49.4 km to 52 km. The precise epicenter coordinates also differ by a few hundred meters between the GFZ and JMA reports. As additional seismic data are processed, authorities will likely release a definitive assessment, but the current public records reflect these competing preliminary figures.
