Iwo-jima Volcano
Updated: Sep 29, 2025 22:29 GMT -
caldera
Volcano Islands (Japan), 24.75°N / 141.29°E 
Summit height: 161 m / 528 ft
Current status: erupting (4 out of 5)
Last update: 10 Sep 2025 (Smithsonian / USGS Weekly Volcanic Activity Report)
Ioto (硫黄島, also known as Iwo-jima) volcano is a triangular-shaped, flat, 8 km long and up to 4.5 wide volcanic island stretching NE-SW. It is surrounded by steep cliffs under the sea, which belong to a 9-km-wide submarine caldera. The volcano is located 1250 km south of Tokyo in the central Volcano Islands of the Izu-Marianas arc.
The summit of Iwo-jima is Suribachi-yama at 160 m.
Parts of the caldera have been experiencing remarkably strong uplift (up to more than 1 meter per year and averaging 25 cm / year over several centuries). There is strong hydrothermal activity at present, at fumaroles along a NE-SW zone cutting through Moto-yama. Many phreatic eruptions occurred in historic times, mostly from vents on the west and NW sides of the island.
Iwo-jima was the site of an infamous WWII battle, and the location of a famous image of the raised US flag.
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Iwo-jima volcano eruptions: 2012, 2001, 1982, 1980, 1978, 1976, 1974 (?), 1969 (?), 1967, 1957, 1943
Latest nearby earthquakes
| Date and Time | Mag / Depth | Distance / Location | |||
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Background
Ioto, Iwo-jima, and Io-jima are among many spellings of the same name, which means "Sulfur Island", as many other volcanic islands in Japan. Another name, to distinguish it better is Ogasawara Io-jima.Ioto volcano has produced trachyandesitic and trachytic lavas that are more alkalic than those of other Izu-Marianas arc volcanoes.
The island has undergone dramatic uplift for at least the past 700 years caused by resurgent doming of the caldera. A shoreline landed upon by Captain Cook's surveying crew in 1779 is now 40 m above sea level. The Moto-yama plateau on the NE half of the island consists of submarine tuffs overlain by coral deposits and forms the island's high point.
During 1911 to 1952, uplift was 11 cm per year and reached 33 cm per year between 1952 and 1968. More recent studies show that the center of the Iwo-jima caldera is experiencing subsidence while the surrounding areas are uplifted.
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Sources:
- Smithsonian / GVP volcano information
- Ukawa et al (2005) "Long-term geodetic measurements of large scale deformation at Iwo-jima caldera, Japan", Journal of Volcanology and Geothermal Research, Volume 150, Issues 1-3, Pages 98-118
- NEWHALL, C. G. & DZURISIN, D. (1988) "Historical Unrest at Large Calderas of the World", Volumes 1 & 2, USGS Bulletin 1855. x + 598 pp., v + pp. 599-1108.
Iwo-jima Volcano Photos
... where we raise our glasses to a great 2 weeks tour and enjoy the first of many delicious Italian meals. (Photo: Ingrid Smet)
Significant volcanic eruptions: Iwo-jima volcano
In the past 10,000 years, Iwo-jima has had at least 26 confirmed volcanic eruptions, out of which 25 are documented by historical records, while the others can be inferred from geological evidence.
Additionally, there are 6 uncertain or discredited eruptions from Iwo-jima volcano.
Additionally, there are 6 uncertain or discredited eruptions from Iwo-jima volcano.
The table below lists all known eruptions (date in bold face) of Iwo-jima volcano since around 1900. Updates on the most recent volcanic activity of Iwo-jima can be found on the news page of Iwo-jima volcano.
| Date | Note | VEI | Deaths | Damage | |
|---|---|---|---|---|---|
Historical obs./docs. | 1 | ||||
| Off SE coast Historical obs./docs. | 1 | ||||
| Off SE coast Historical obs./docs. | 1 | ||||
| Asodai Sinkhole Historical obs./docs. | 1 | ||||
?? | Uncertain Eruption Historical obs./docs. | 1 | |||
| Asodai Sinkhole Historical obs./docs. | 1 | ||||
| Kianohana Beach (N part of the island) Historical obs./docs. | 1 | ||||
?? | Uncertain Eruption Historical obs./docs. | 0 | |||
| Asodai Historical obs./docs. | 1 | ||||
| Asodai Historical obs./docs. | 1 | ||||
?? | Uncertain Eruption Historical obs./docs. | 1 | |||
?? | Uncertain Eruption | 1 | |||
| Off SE coast and Idogahama (NW coast) Historical obs./docs. | 1 | ||||
| Asodai area Historical obs./docs. | 1 | ||||
| NE side Historical obs./docs. | 1 | ||||
?? | Uncertain Eruption | 1? | |||
| West side (Asodai) Historical obs./docs. | 1 | ||||
| NW side (Idogahama beach) Historical obs./docs. | 1 | ||||
| Kitanohara Historical obs./docs. | 1 | ||||
| West side (Asodai) Historical obs./docs. | 1 | ||||
| West side (Asodai) Historical obs./docs. | 1 | ||||
?? | Uncertain Eruption | 0 | |||
Historical obs./docs. | 1 | ||||
| West side (Asodai) Historical obs./docs. | 1 | ||||
| West side (Asodai) Historical obs./docs. | 1 | ||||
| Chidoriga-hara Historical obs./docs. | 1 | ||||
| North and west sides near the coast Historical obs./docs. | 1 | ||||
| SW side at Chidoriga-hara Historical obs./docs. | 1 | ||||
| NW side near the coast Historical obs./docs. | 1 | ||||
| West side (Asodai) Historical obs./docs. | 1 | ||||
Remark:
Our list of volcanic eruptions closely follows the database of eruptions of the Smithsonian's Global Volcanism Project (GVP), the internationally most recognized data source for volcanic eruptions, but also includes significant eruptive episodes or related volcano events. "Volcanic eruptions" are usually to be understood as sequences of individual eruptive episodes that can follow each other, or even overlap (if several vents are involved), and can last many years, decades or even longer. For example, the current activity of Stromboli volcano is understood as a single eruption that has been ongoing since 1934.
Sources: NOAA National Centers for Environmental Information (NCEI), Global Significant Volcanic Eruptions Database. doi:10.7289/V5TD9V7K | Global Volcanism Project / Smithsonian Institution
Eruptions of Iwo-jima volcano
2001 eruption
A submarine eruption occurred from 3 vents SE of Iwo-jima volcano on 21 September 2001. The activity built 10 m diameter pyroclastic cone on that day. Until 19 October, there was no further activity, but on 19 October a small phreatic eruption occurred at Idogahama, the name of a beach on the NW coast of the island. the explosion formed a new crater 10 m wide and 2-3 m deep.
A submarine eruption occurred from 3 vents SE of Iwo-jima volcano on 21 September 2001. The activity built 10 m diameter pyroclastic cone on that day. Until 19 October, there was no further activity, but on 19 October a small phreatic eruption occurred at Idogahama, the name of a beach on the NW coast of the island. the explosion formed a new crater 10 m wide and 2-3 m deep.
1982 eruption
On 9-10 March 1982, 5 phreatic eruptions occurred from vents on the NW shore of Iwo-jima island.
On 9-10 March 1982, 5 phreatic eruptions occurred from vents on the NW shore of Iwo-jima island.
1957 eruption
A phreatic eruption occurred at Iwo-Jima volcano on 28 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 from a single crater. A second crater formed by collapse 50 minutes after the eruption ended. The collapse crater was 30 m wide and 15 m deep. Gas emissions increased on 31 March, and 3 dead birds were found in the crater.
Source: Gilbert Corwin, and H. L. Foster (1959) "The 1957 explosive eruption on Iwo Jima, Volcano Islands", American Journal of Science, Vol. 257, pp. 161-171 ...more info
A phreatic eruption occurred at Iwo-Jima volcano on 28 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 from a single crater. A second crater formed by collapse 50 minutes after the eruption ended. The collapse crater was 30 m wide and 15 m deep. Gas emissions increased on 31 March, and 3 dead birds were found in the crater.
Source: Gilbert Corwin, and H. L. Foster (1959) "The 1957 explosive eruption on Iwo Jima, Volcano Islands", American Journal of Science, Vol. 257, pp. 161-171 ...more info
Iwo-jima Volcano FAQ
+When was the last eruption of Iwo-jima volcano?
The last confirmed eruption of Iwo-jima occurred during 2023 - 2024.
+How often does Iwo-jima volcano erupt?
Since 1889, Iwo-jima volcano has had at least 25 historically documented eruptions. This means that it erupts on average every 5.4 years.
+How active is Iwo-jima volcano at present?
Iwo-jima volcano is relatively active: Since 1900, it has had 23 eruptions, and been active during 23 years out of 126 as of now. This means, Iwo-jima has been in eruption one in 5.5 years on average. The last eruption was from 2023 until 2024 and ended 2 years ago.
+When was the largest eruption of Iwo-jima volcano?
The largest eruption of Iwo-jima volcano in historic times occurred during 2023 - 2024. It only has a VEI (Volcanic Explosivity Index) of 1, likely because it was a mainly effusive eruption generating lava flows but very little ash.
Latest satellite images
Iwo-jima Volcano Maps
Below is a selection of maps showing the location and surroundings of the volcano at various resolutions based on aerial-imagery / terrain maps. Feel free to use them for non-commercial purposes on your blog or website as long as you credit them with a link back to this page (click to copy it).
Satellite/aerial-type map of Iwo-jima volcano (world scale)
Terrain-type map of Iwo-jima volcano (world scale)
Satellite/aerial-type map of Iwo-jima volcano (region scale large)
Terrain-type map of Iwo-jima volcano (region scale large)
Satellite/aerial-type map of Iwo-jima volcano (region scale medium)
Terrain-type map of Iwo-jima volcano (region scale medium)
Satellite/aerial-type map of Iwo-jima volcano (region scale small)
Terrain-type map of Iwo-jima volcano (region scale small)
Satellite/aerial-type map of Iwo-jima volcano (local scale large)
Terrain-type map of Iwo-jima volcano (local scale large)
Satellite/aerial-type map of Iwo-jima volcano (local scale medium)
Terrain-type map of Iwo-jima volcano (local scale medium)
Satellite/aerial-type map of Iwo-jima volcano (local scale small)
Terrain-type map of Iwo-jima volcano (local scale small)
Satellite/aerial-type map of Iwo-jima volcano (scale of 10s of km)
Terrain-type map of Iwo-jima volcano (scale of 10s of km)
Satellite/aerial-type map of Iwo-jima volcano (scale of 20-40 km)
Terrain-type map of Iwo-jima volcano (scale of 20-40 km)
Satellite/aerial-type map of Iwo-jima volcano (scale of approx. 10-20 km)
Terrain-type map of Iwo-jima volcano (scale of approx. 10-20 km)
Satellite/aerial-type map of Iwo-jima volcano (scale of 5-10 km)
Satellite/aerial-type map of Iwo-jima volcano (scale of few kilometers)
