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Tsunami waves up to 60 cm (2 feet) hit Japan’s Izu Islands following shallow M5.0 earthquake

Tsunami waves up to 60 cm (2 feet) hit Japan’s Izu Islands following M5.0 earthquake october 9 2023

Japan’s Izu Islands and parts of the Pacific Coast near Tokyo experienced tsunami waves up to 60 cm (2 feet) in height triggered by a shallow M5.0 earthquake that occurred at 20:26 UTC on October 8, 2023 (05:26 local time, October 9). The quake’s epicenter was situated near the uninhabited Torishima Island at the southern end of the Izu chain and is part of an ongoing earthquake swarm in the region.

Tsunami waves were recorded in various regions with Hachijo and some other islands in Izu, as well as an island in the Ogasawara chain in the Pacific Ocean south of Tokyo, experiencing up to 60 cm (2 feet) in wave height. In Nichinan, Miyazaki Prefecture the waves reached 20 cm (0.6 feet), Tateyama, Chiba Prefecture, measured 30 cm (1 foot), while Tosashimizu, Kochi Prefecture, and Nakano Island in Kagoshima Prefecture saw waves of 40 cm (1.3 feet).

The tsunami alert prompted evacuation directives in five coastal cities in Kochi and 12 municipalities in Chiba, which were lifted at 03:00 UTC (12:00 LT).

Local authorities reported no injuries or damages on the islands or in the prefectures of Chiba, Kochi, Kagoshima, or Miyazaki. However, several small boats in the Hachijo and Kozu islands, part of the Izu chain, were overturned, with no injuries reported.

Following the quake (preliminary magnitude 5.0), the Japan Meteorological Agency (JMA) predicted a 1 m (3.3 feet) tsunami for Chiba.

The occurrence follows a similar event on October 5 when small tsunami waves arrived in parts of the Izu Island chain following an earthquake registered by the JMA as M6.5. USGS reported it as M6.1

According to the USGS, this sequence produced at least 72 earthquakes since October 1. It includes 3 earthquakes with magnitudes above 6 (M6.0, M6.1, and M6.1), and 28 earthquakes with magnitudes between 5 and 6.

earthquake swarm izu islands october 1 - 9 2023
Earthquakes reported by USGS from October 1 – 9, 2023. Credit: TW/SAM, Google
earthquake swarm izu islands october 1 - 9 2023 zoom
Earthquakes reported by USGS from October 1 – 9, 2023. Credit: TW/SAM, Google


1 Small tsunami seen on islands near Tokyo, other Pacific coast areas – The Japan Times – October 9, 2023

2 Tsunami Information Statement Number 1 – NWS Pacific Tsunami Warning Center Honolulu, HI – October 8, 2023 at 23:39 UTC

Featured image credit: BuHMKq3qOmvlYXx (stillshot)

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