A magnitude 6.1 earthquake struck off Japan's eastern Kanto coast on Friday evening, November 6, with shaking felt in central Tokyo, the Japan Meteorological Agency (JMA) said, in a report carried by China's Xinhua news agency. No tsunami alert was issued.

Source: Xinhua via EIN News

The United States Geological Survey (USGS), in its reviewed solution, put the quake at magnitude 6.1 at 10:39 UTC (7:39 p.m. Japan time), centred 144 kilometres southeast of Hasaki, in Chiba prefecture, at a depth of 29 kilometres, at coordinates 34.968° N, 142.118° E.

6.1magnitude of the earthquake off the Kanto coast (USGS, JMA)
144 kmsoutheast of Hasaki, Chiba — the epicentre's distance offshore
29 kmdepth of the quake in the USGS reviewed solution
10:39 UTCorigin time — 7:39 p.m. Friday in Japan
27public felt reports logged by the USGS at the time of its snapshot

The USGS recorded reported shaking as Light (intensity IV) from its public felt reports, while its ShakeMap modelled a strongest contour of Strong (VI) near the epicentre offshore — modelled contours show where shaking was expected, not damage. The USGS issued a green PAGER alert for the event, indicating a low likelihood of casualties or damage, according to the Watchers' summary of the USGS data.

India's National Centre for Seismology (NCS) also logged the quake, reporting it at 4:09 p.m. Indian time about 145 km from Choshi, Chiba, and said the JMA had issued a tsunami forecast flagging possible slight sea-level changes along the eastern Kanto coastline — while stressing that no tsunami warning or advisory had been triggered. The agency reports available on Friday carried no reports of damage or casualties from the quake.

What is solid

  • A magnitude 6.1 earthquake struck off Japan's Kanto coast at 10:39 UTC on Friday, November 6, centred offshore southeast of Hasaki, Chiba (USGS, JMA via Xinhua, NCS)
  • Shaking was felt in central Tokyo (JMA via Xinhua)
  • No tsunami warning, advisory or alert was issued (Xinhua/JMA reports; NCS report)

What is only claimed

  • Depth and distance figures vary slightly by agency and revision: the USGS reviewed solution gives 144 km southeast of Hasaki at 29 km depth, while early reports put the depth at 10 km and the NCS measured the epicentre about 145 km from Choshi
  • One Indian aggregator report of a separate morning quake injuring more than 40 people in Tokyo could not be confirmed by any second agency source and is not relied on in this report

The quake was one of two magnitude 6.1 events in the USGS catalog for Friday: a daily earthquake roundup based on the USGS catalog also recorded a magnitude 6.1 quake deep under Fiji, with no damage reported from either event. Japan sits on the Pacific "Ring of Fire" and experiences strong offshore earthquakes regularly; its building codes and early-warning systems are designed for events of this size.

What happens next is monitoring: the JMA routinely watches for aftershocks after a quake of this size, and the USGS figures may be revised again as more data arrives. As of Friday's agency reports, there was no damage or casualty toll to update — if that changes, it will be reported as a new development.