A magnitude 7.0 earthquake struck deep beneath the Pacific Ocean near Japan's remote Ogasawara Islands, about 1,000 km (620 miles) south of Tokyo, on Sunday, with no threat of a tsunami, the Japan Meteorological Agency (JMA) said.

Source: Japan Meteorological Agency via Xinhua, Oct 25

The preliminary magnitude was recorded at around 11:10 a.m. local time (02:10 GMT) on Sunday, in waters west of the island chain and at a depth of about 470 km (290 miles), the agency said. Earlier, the European-Mediterranean Seismological Centre (EMSC) reported a magnitude 6.3 earthquake in the Bonin Islands, the same island group.

Source: JMA and EMSC reporting, Oct 25

7.0Preliminary magnitude recorded by the JMA
470 kmDepth below the Pacific — a deep-focus earthquake
3JMA seismic intensity on Chichijima and Hahajima, on a scale of 0 to 7
1,000 kmApproximate distance of the islands south of Tokyo

Felt widely, but no casualties or damage reported

The quake measured 3 on Japan's seismic intensity scale on Chichijima and Hahajima, the two inhabited islands of the group, which is also known as the Bonin Islands and is administered by the Tokyo Metropolitan Government. There were no immediate reports of casualties or damage.

Source: JMA reporting, Oct 25

Despite the distance, the tremor was felt across a wide area of eastern and north-eastern Japan, Kyodo News reported, because seismic waves are believed to have travelled through the Pacific plate. Deep earthquakes off the Ogasawara Islands can be felt far away: a magnitude 7.9 quake at a depth of 664 km in the same region in 2015 was felt across almost all of Japan and stopped elevators in Tokyo, though it killed no one.

The islands lie in the seismically active Izu-Bonin-Mariana region of the western Pacific, where the Pacific plate moves beneath the Philippine Sea plate. Japan sits where four tectonic plates meet, and about 10 per cent of the world's earthquakes of magnitude 6 or higher strike in or around the country.

Source: JMA / background reporting, Oct 25

What is solid

  • A magnitude 7.0 earthquake struck west of the Ogasawara Islands at about 11:10 a.m. local time on Sunday at a depth of about 470 km (JMA)
  • The JMA said there was no threat of a tsunami, and there were no immediate reports of casualties or damage
  • Shaking reached JMA intensity 3 on Chichijima and Hahajima and was felt across eastern and north-eastern Japan (Kyodo News)

What is only claimed

  • The first magnitude readings differed by agency: the EMSC initially reported magnitude 6.3 for the Bonin Islands event, while the JMA's preliminary figure was 7.0 — early readings are routinely revised
What to watch

Japanese authorities routinely revise early magnitude and depth figures as more data arrives. The depth of this quake — about 470 km down — is the main reason a magnitude 7.0 event caused no reported damage: the energy was released far below the islands rather than near the surface.