Iwo-jima Volcano | John Seach


Volcano Islands, Japan

24.75 N, 141.33 E
summit elevation 160 m

Iwo-jima volcano is located 1250 km south of Tokyo, and consists of a low and flat volcanic island of 8.5 km long in NE-SW and 4.5 wide, surrounded by steep cliffs under the sea. The summit of Iwo-jima is Suribachi-yama at 160 m. Iwo-jima was the site of a infamous WWII battle, and the location of a famous image of the raising of the US flag.

Uplifting rate of Iwo-jima  island is very high. During 1911 to 1952 uplift was 11 cm per year. Uplift was 33 cm/ year between 1952 and 1968.

The island is almost entirely composed of lava flows, pyroclastic rocks, and volcanic deposits.

In 2021 twenty-four ships washed ashore on the western side of Iwo-Jima Island, which were sunk in the second world war battle for Iwo-Jima. The ships were mobilised by underwater eruptions of Fukutoku-Okanoba volcano.

2001 Eruption
A submarine eruption occurred at Iwo-jima volcano on 21st September 2001. Three vents showed activity SE of the island. a 10 m diameter pyroclastic cone was formed. Between 21 September and 19th October 2001 there was no activity at the volcano. On of 19th October a small phreatic eruption occurred at Idogahama, a beach on the NW coast of the island, forming a crater 10 m long and 2-3 m deep.

1982 Eruption
On 9-10 March 1982 five phreatic eruptions occurred on the NW shore of the island.

1957 Eruption
A phreatic eruption occurred at Iwo-Jima volcano on 28th March 1957. The eruption occurred without warning 2 km NE of Suribachi-yama. The eruption lasted for 65 minutes and ejected material 30 m high. Eruptions occurred from a single crater. A second crater formed by collapse 50 minutes after the eruption ended. On 31st March gas emissions increased, and three dead birds were seen in the main crater. The main crater was 30 m wide and 15 m deep.

Further Reading
Ueda, H., Nagai, M. and Tanada, T., 2018. Phreatic eruptions and deformation of Ioto Island (Iwo-jima), Japan, triggered by deep magma injection. Earth, Planets and Space, 70(1), pp.1-15.

Corwin, G. and Foster, H.L., 1959. The 1957 explosive eruption on Iwo jima, Volcano Islands. American Journal of Science, 257(3), pp.161-171.

Iwo-jima Volcano Eruptions

2001, 1982, 1980, 1978, 1976, 1974?, 1969?, 1967, 1957, 1943