The Island That Makes Continental Crust: Nishinoshima

The lava coming out of Nishinoshima in its first three eruptive episodes ran 59.2 to 59.9 weight per cent silica. That is andesite, and it is roughly the composition of the Earth's continental crust. The volcano producing it sits on ocean floor a thousand kilometres from Tokyo, on crust about twenty-one kilometres thick, with no continent within reach. It is manufacturing continent from the sea up.

Silence Index — D-045

Effectively unvisited

Ranks 4 of 99 scored dossiers — quieter than 97% of the others we have scored. A low score is not a warning; it describes who else will be standing next to you.

How the total is weighted. These are the fixed weights of the four inputs, the same on every dossier — not this place’s scores. We do not publish per-input bars, because the per-input values were never recorded article by article and inventing four plausible numbers that sum to the total would be a fabrication dressed as a chart.

Footfall pressure — visitors measured against the ground that absorbs them30%

Access friction — permits, caps, seasons, boats, weather windows30%

Acoustic floor — how close the nearest engine is20%

Unresolved questions — what the record still cannot settle20%

This dossier was scored before 2 September 2026, when the fourth input became night darkness. It keeps the input it was reasoned with until it is re-scored at its next source re-check; the methodology page records the change.

The index is a desk instrument scored by this publication, not a field measurement. How it is calculated, and where it fails.

This is a desk-researched dossier. Nobody from this publication has been to Nishinoshima, and under the protocol in force nobody could go without a research programme, a government authorisation and a swim. It is built from the Japan Coast Guard's marine volcano database, the Japan Meteorological Agency's volcanic activity reports, the Ministry of the Environment's Kanto Regional Office, the Cabinet Office's ocean policy secretariat, the Ministry of Land, Infrastructure and Transport's white paper, UNESCO, the Smithsonian Institution's Global Volcanism Program, NASA Earth Observatory, JAMSTEC and peer-reviewed volcanology and botany.

What is actually happening down there

Nishinoshima is the emergent summit of a large submarine volcano in the Ogasawara arc, part of the Izu-Bonin-Mariana system where the Pacific plate goes down beneath the Philippine Sea plate. The visible island is a very small fraction of the edifice; a southern cone rises to within 214 metres of the sea surface nine kilometres to the south-south-east.

The current sequence began in November 2013, when a new vent broke the surface as a small islet beside the existing island. The two merged before the year was out — the Global Volcanism Program gives 24 December 2013, the Ministry of Land, Infrastructure and Transport's white paper gives 26 December. Within about a year the new lava had buried most of the old island beneath it.

Maeno and colleagues, writing in Frontiers in Earth Science in 2021, divide what followed into four episodes. The first ran from November 2013 to December 2015 and built the island out to about 2.7 square kilometres and roughly 150 metres high. The second, April to August 2017, took it to about 2.9 square kilometres. The third was a single week in July 2018. The fourth, from December 2019 to August 2020, was by far the largest: about 4.4 square kilometres and around 250 metres, with a total erupted volume of some 0.2 cubic kilometres.

Magma discharge rates give a sense of the difference in scale. Episode one averaged about 2 × 10⁵ cubic metres a day with peaks around 5 × 10⁵. Episode three managed 3 to 4 × 10⁴. In late June and July 2020, episode four hit the order of 10⁶ cubic metres a day. Plumes went to 4.6 kilometres by late June, 6.1 kilometres on 8 and 9 July by the Global Volcanism Program's account, and NASA reported ash detected at 8,300 metres on 4 July — the highest since the volcano broke the water line in 2013 — with volcanic bombs thrown 2.5 kilometres from the island.

The chemistry, which is the point

Continental crust averages something close to andesite in composition. Ocean crust does not: it is basalt. The standing question in petrology is how you get from one to the other, since continents have to have been made from something, and the intra-oceanic island arcs are the leading candidate for the factory.

Nishinoshima is unusually direct evidence because it skips the complications. Episodes one to three erupted 59.2 to 59.9 weight per cent SiO₂ — andesite, of low viscosity, with olivine absent. There is no continent nearby to contaminate the melt, no thick pile of older crust for the magma to assimilate on the way up. What comes out is what the mantle wedge and the thin crust above it are making.

JAMSTEC's account of the underlying mechanism is that crustal thickness determines magma type in oceanic arcs: thin crust of ten to twenty kilometres produces andesitic magmas, while crust around thirty-five kilometres thick produces basaltic lavas. A 2023 study in the same journal family puts the crust beneath Nishinoshima at about 21 kilometres and describes the volcano as one of the closest arc volcanoes to the mantle anywhere on Earth. Its authors draw the inference all the way out: the rate of continental crust accumulation would have been greatest soon after subduction began on Earth, when most crust was still thin.

Episode four broke the pattern, and that is scientifically the most interesting part. The 2020 eruption shifted to 54.8 to 55.1 weight per cent — basaltic andesite, carrying olivine phenocrysts, with submarine deposits spanning basalt through to dacite and clear textural evidence of basaltic and andesitic magma mingling within the crust. Something more mafic arrived from below and mixed. The factory is not running a single fixed recipe.

What popular coverage gets wrong

The line that circulates most widely about Nishinoshima is that the eruption expanded Japan's territory, and in the more excitable versions its exclusive economic zone. This turns up in aggregator coverage, in list articles about countries gaining land, and in a steady trickle of social posts every time the volcano does something photogenic.

The Ministry of Land, Infrastructure and Transport publishes the actual figure in its own white paper. The territorial sea gained by the eruption, as measured on 25 March 2015, was approximately 2.5 square kilometres. That is a rounding error against a national maritime area measured in millions.

The exclusive economic zone did not change at all, and could not have. Nishinoshima was already an island above water before 2013 — it has been mapped since the eighteenth century and its pre-eruption summit stood 25 metres above sea level. It was already generating a full territorial sea and EEZ under the law of the sea. Growing an existing island moves its baseline outward by the width of the new coast; it does not create an entitlement that was not there.

The related error is calling this a new island. The Japan Coast Guard's own database records the same volcano building an islet in December 1973 that measured 550 metres east to west and 200 to 400 metres north to south, with an area of 121,000 square metres and an elevation of 52 metres. By January 1999 wave erosion had reduced that feature to 250,100 square metres and 15.2 metres of elevation. Nishinoshima has done this before, and the sea took most of it back.

Whether the sea takes this one back is an open question with a published threshold. Maeno and colleagues estimate that surviving marine erosion requires long-lasting voluminous lava effusion at an annual average discharge rate on the order of at least 10⁴ to 10⁵ cubic metres a day. The 2013–20 episodes cleared that comfortably. Since October 2023 the volcano has not erupted at all.

The current state, which is quiet

The most recent confirmed eruption was on 4 October 2023, when the Japan Coast Guard observed grey ash-and-gas plumes rising to 1.5 kilometres. The Japan Meteorological Agency's annual report for 2025 records no eruptions during that year. What it does record is a crater lake, changing colour through the year from ash-white in the early months to brown-tinged in September and grey-green from October, with steam rising continuously from its surface; white fumaroles and sulphur sublimation around the crater, concentrated on the eastern inner wall; and discoloured water extending three to 4.6 kilometres from the island, occasionally with floating pumice.

Land surface temperature near the island now shows almost no difference from its surroundings. The alert in force is a crater-area entry prohibition, with a maritime warning radius of 0.9 nautical miles. The Japan Coast Guard's most recent aerial observation logged in its database was on 16 April 2026, showing the pyroclastic cone and central crater.

A volcano with a crater lake and no thermal anomaly is a volcano between episodes, not one that has finished. On the record of the last decade the reasonable expectation is another episode.

The strictest landing rule in the Pacific

Nishinoshima is one of the five components of the Ogasawara Islands World Heritage property, inscribed in 2011 under criterion (ix) for ongoing evolutionary processes in oceanic island ecosystems. The whole property covers 7,939 hectares, of which 6,358 are terrestrial and 1,581 marine, and it is explicitly a serial site: more than thirty islands in three groups, plus Kita-iwoto and Minami-iwoto, plus isolated Nishinoshima.

On 14 June 2016 the Ogasawara Islands World Natural Heritage Science Committee, with the Ministry of the Environment, the Forestry Agency, the Tokyo Metropolitan Government and Ogasawara Village, issued a landing protocol. Its provisions are worth setting out because they are unusual even by the standards of biosecurity regimes.

• Landing plans must use the minimum number of people and the minimum frequency necessary for the research being done.
• Footwear, clothing and bags should be new, or equivalent to new; where that is impossible, they must be disinfected by freezing, alcohol washing or similar, ideally prepared in clean-room conditions.
• Before landing, people and cargo must be fully submerged in seawater — a wet landing in the literal sense, intended to drown or wash off anything hitching a ride.
• Plans are subject to third-party inspection by government agencies and experts.

The Cabinet Office adds the legal layer: Nishinoshima falls within the special protection zones of Ogasawara National Park, parts of the pre-eruption island are national forestland under Forestry Agency jurisdiction, and access is restricted to academic research and comparable activity with Ministry of the Environment authorisation. There is no tourist route and no private landing.

The ecosystem that was there, and the one that is

The reason for the protocol is that this island is one of the very few places where the assembly of a terrestrial ecosystem can be watched from zero.

Before 2020 there was a population of Eleusine indica, goosegrass, on the old part of the island. A genetic study published in 2026 sampled 25 individuals and found every one of them carrying a single chloroplast haplotype — the signature of a population founded by one seed, or at most a very few, in a single rare dispersal event. The closest related populations were in the Ogasawara Islands 130 kilometres away, then Okinawa, then Indonesia, implying a migration route across an extraordinary distance. The likely vector was a seabird: brown boobies, whose feathers and feet the species' one-to-two-millimetre seeds stick to when damp.

That population occupied roughly half a hectare, and the 2019–20 eruption buried it under ash and lava. It is gone. The study exists because the samples were taken before.

A survey of the island's terrestrial biota in 2021, flown by unmanned aircraft, found the entire area covered by lava and ash with no vegetation established, some fungal structures present, and seabirds back: brown and masked boobies, brown noddy, sooty tern and great crested tern, with wedge-tailed shearwaters detected acoustically. One decomposing booby carried fly pupae and plant seeds in its digestive tract — the beginning of a nutrient cycle.

The survey's most uncomfortable finding was that seabird breeding success appeared extremely low, and its authors raised the possibility that Nishinoshima is now an ecological trap: an island attractive enough to nest on and too hostile to fledge chicks from. Birds are the mechanism that brings seeds, soil-forming nutrients and eventually a food web. If they keep arriving and keep failing, the ecosystem does not restart; it stalls.

Why the Silence Index is 92

This is close to the ceiling and it is earned by exclusion rather than by remoteness alone. Nishinoshima is uninhabited, has no landing site, no anchorage worth the name and no permitted visitors; the nearest inhabited land is Chichijima, 130 kilometres east, itself reachable from Tokyo only by a ferry that takes about a day. There is no artificial light within a hundred kilometres, no road, no structure, no track.

What stops it reaching the archive's ceiling is that this is an active volcano with a large seabird colony re-establishing on it, so the acoustic floor is not low; and that it is intensively monitored, with Coast Guard aircraft overhead several times a year. Nobody goes, but the place is watched closely and continuously, which is a different condition from being unobserved.

What to hold onto

Three things, in order of how well they are established.

First, the chemistry is solid and it is the reason this island matters. An intra-oceanic arc volcano on twenty-one kilometres of crust, with no continent in reach, has been erupting magma at continental-crust silica content. That is as close to watching the process as anyone is likely to get.

Second, the territorial claim is not the story and never was. Two and a half square kilometres of territorial sea, and no change to the exclusive economic zone.

Third, the ecological experiment is running and the early results are not encouraging. The one plant population that had established itself over an unknown span of decades was destroyed in a single episode, and the birds that would bring the next one appear to be failing to breed. Whether that is a temporary phase of a young island or a durable trap is the thing worth watching, and it will be watched by people who have to swim ashore to do it.

The Traveler's Panel · checked 14 August 2026

Changing information. Prices, permits, seasons and road access change, sometimes at short notice. Everything here is a starting point for your own confirmation — not a quote, and not a guarantee. Verify with the operator and the relevant official body before you book.

Can you visit	No. Landing requires Ministry of the Environment authorisation for research
The wet landing rule	People and cargo must be fully submerged in seawater before going ashore
Current activity	No eruptions in 2025. Crater lake, fumaroles, discoloured water to 4.6 km
Last eruption	4 October 2023, ash-and-gas plumes to 1.5 km
Warning zone	Crater entry prohibited; 0.9 nautical mile maritime warning radius
Protected status	UNESCO World Heritage component and Ogasawara National Park special zone

Getting there — Tokyo → Ogasawara ferry → Chichijima → 130 km west by chartered vessel (landing by authorisation only)

1. There is no public access. Nishinoshima is one of five components of the Ogasawara Islands World Heritage property, sits within the special protection zones of Ogasawara National Park, and parts of the pre-eruption island are national forestland under Forestry Agency jurisdiction. Access is restricted to academic research and comparable activity with Ministry of the Environment authorisation.
2. The 2016 landing protocol is the binding document. It requires the minimum number of people and the minimum frequency, new or clean-room-disinfected footwear, clothing and bags, full seawater submersion of people and cargo before landing, and third-party inspection of the plan by government agencies and experts.
3. The inhabited Ogasawara Islands are reachable — Chichijima and Hahajima have populations, harbours and accommodation — and they are the closest anyone without a research permit will get. Chichijima lies about 130 km east of Nishinoshima.
4. A maritime warning radius of 0.9 nautical miles is in force around the island. Vessels are advised to keep clear even when the volcano is not erupting.
5. Aerial observation is done by the Japan Coast Guard several times a year and the imagery is published in its marine volcano database, which is the practical way to see the island.

Indicative costs — verify before booking

Visiting Nishinoshima	Not possible without a research authorisation
The Ogasawara Islands	Reachable by ferry from Tokyo to Chichijima; check the operator directly
Research access	Ministry of the Environment authorisation, plus third-party plan inspection
Note	No operator sells access to Nishinoshima. Anyone offering it is offering something illegal

What to pack

• Nothing, because you are not going. The honest version of this list is the 2016 protocol: new or freezer-and-alcohol-disinfected footwear, clothing and bags, ideally prepared in clean-room conditions.
• For the inhabited Ogasawara Islands, the practical constraint is the ferry schedule rather than equipment; the crossing is long and infrequent and shapes the whole trip.
• Binoculars, if you are on a vessel anywhere near the warning radius. Discoloured water extends three to five kilometres from the island and is the most visible sign of activity.

Where to stay

There is nowhere to stay, no shelter and no anchorage on Nishinoshima, and there is no prospect of any. The nearest accommodation is on Chichijima, about 130 kilometres east, which has a resident population of around two thousand and is reached from Tokyo by ferry; Hahajima, further south, has about 2,500 residents and a harbour. Both are ordinary inhabited Japanese islands with guesthouses and small hotels, and both are a long way from anything. Nishinoshima itself is visited only by Coast Guard aircraft, research vessels and, roughly once a decade, a very small number of people who have swum the last few metres.

Safety & responsible travel

• Do not repeat the claim that the eruption expanded Japan's territory or EEZ. The figure published by Japan's own transport ministry is about 2.5 km² of territorial sea, and the exclusive economic zone was unchanged.
• Do not call it a new island without qualification. Nishinoshima existed before 2013 with a 25 m summit, and the same volcano built and lost an islet between 1973 and 1999.
• If you are ever in a position to land, the wet-landing rule is not theatre. A single seed in a boot tread on an island with no vegetation is a permanent change to a UNESCO property inscribed specifically for ongoing evolutionary processes.
• Do not fly a drone near the island from a passing vessel. It is inside a national park special protection zone and a maritime warning area.
• Treat the seabird colony as fragile even though it looks like a recolonisation success. The 2021 survey found breeding success extremely low and raised the possibility that the island is now an ecological trap.

Nearby, and quieter

Chichijima and Hahajima are the inhabited core of the Ogasawara group and carry most of the endemism the World Heritage inscription was written for — the property was listed under criterion (ix) for evolutionary processes rather than for scenery. Kita-iwoto and Minami-iwoto in the Kazan group are the other isolated components, both uninhabited. The submarine southern cone of the same volcano rises to within 214 metres of the surface nine kilometres south-south-east of Nishinoshima and is invisible from the surface. Tokyo, a thousand kilometres north, is the same prefecture.

Getting there, in order

• 1Tokyo
• ↓
• 2Ogasawara ferry
• ↓
• 3Chichijima
• ↓
• 4130 km west by chartered vessel (landing by authorisation only)

Each leg is a separate booking and a separate chance to be weathered out. Build spare days into the chain, not onto the end of it.

Where it is

Nishinoshima, Ogasawara Islands, Japan · 27.2439°N 140.8797°E · Open in Google Maps · OpenStreetMap

Key locations

• Nishinoshima — the emergent summit of a large submarine volcano, about 4.4 km squared in 2020
  27.2439°N 140.8797°E
• Chichijima — the nearest inhabited island, about 130 km east, population around 2,000
  27.0689°N 142.2139°E
• Hahajima — the second inhabited island of the group, south of Chichijima
  26.6683°N 142.1539°E
• Hahajima harbour — the southern group's port, the practical end of the ferry chain
  26.6944°N 142.1528°E

Coordinates are for orientation and are accurate to roughly the width of the feature named, not to a doorway. Several of these points are inside protected areas or need a permit, a guide or a boat — read the access notes above before you plan a route to any of them.

Sources & further reading — checked 14 August 2026

1. Maeno et al. — Eruption Style Transitions During the 2019–2020 Eruptive Activity at Nishinoshima, Frontiers in Earth Science 9 (2021). The four eruptive episodes and their dates; island area of about 2.7 km² by end 2015, 2.9 km² by August 2017 and 4.4 km² by August 2020; SiO₂ of 59.2–59.9 wt% for episodes 1–3 and 54.8–55.1 wt% for episode 4 with olivine phenocrysts; magma discharge rates per episode; and the 10⁴–10⁵ m³/day threshold for surviving marine erosion
2. Ministry of the Environment, Kanto Regional Office — Nishinoshima landing rules (14 June 2016). The landing protocol agreed by the Ogasawara Islands World Natural Heritage Science Committee with the Ministry of the Environment, Forestry Agency, Tokyo Metropolitan Government and Ogasawara Village: minimum personnel and frequency, new or disinfected footwear and clothing, clean-room preparation, full seawater submersion of people and cargo before landing, and third-party inspection of plans
3. Smithsonian Global Volcanism Program — Nishinoshima. Coordinates 27.2439°N 140.8797°E, elevation 160 m, composite and caldera type, the 1973 submarine eruption and island, the November 2013 emergence of Niijima and its merger with Nishinoshima on 24 December 2013, and the most recent eruption in October 2023 with grey ash-and-gas plumes to 1.5 km observed by the Japan Coast Guard on 4 October
4. Smithsonian Global Volcanism Program — Bulletin report on Nishinoshima, September 2020. The 2020 plume record from about 1,000 m in March to 6.1 km on 8–9 July, lava flows covering all sides of the island, the sequence of Japan Coast Guard overflights, and the 214 m submarine southern cone 9 km SSE
5. Smithsonian Global Volcanism Program — Bulletin report on Nishinoshima, February 2021. The end of the 2019–2020 eruption with last ash emissions on 27 August 2020, JMA confirming no eruptive activity after 5 September, steam plumes over 2 km on Coast Guard overflights of 19 and 23 August, and the reduction of the warning radius from 2.5 to 1.5 km on 18 December
6. Smithsonian Global Volcanism Program — Bulletin report on Nishinoshima, July 2023. The October 2022 ash plume to 3.5 km above the crater rim, Japan Coast Guard fumarole observations in November 2022 and January 2023, the April 2023 ash plumes to 1.9 km, and the discoloured water record
7. Japan Meteorological Agency — Annual volcanic activity report for Nishinoshima, 2025. No eruptions recorded during 2025; the crater lake and its colour changes through the year; white fumaroles and sulphur sublimation on the eastern inner crater wall; discoloured water extending 3 to 4.6 km; the near-absence of a land surface temperature anomaly; and the crater entry prohibition with a 0.9 nautical mile maritime warning radius
8. Japan Coast Guard, Hydrographic and Oceanographic Department — Nishinoshima, marine volcano database. The December 1973 islet at 550 m east-west by 200–400 m north-south, area 121,000 m² and elevation 52 m; its erosion to 250,100 m² and 15.2 m by January 1999; the pre-2013 summit of 25 m; the 160 m high point recorded in December 2018; and aerial observations logged to 16 April 2026
9. Japan Coast Guard — Nishinoshima observation record. The measured area of 2.63 km² in March 2016 and the island's dimensions in September 2014, March 2015 and August 2015, and the 20 November 2013 start of the current eruption
10. Ministry of Land, Infrastructure, Transport and Tourism — white paper column on Nishinoshima and the territorial sea. The figure this dossier uses to correct the territory claim: approximately 2.5 km² of territorial sea added by the eruption as measured on 25 March 2015, with the merger of the new island and Nishinoshima dated 26 December 2013
11. Cabinet Office, Ocean Policy Secretariat — Nishinoshima eruption status. Nishinoshima as an uninhabited island about 1,000 km south of Honshu and 130 km west of Chichijima; its position within the special protection zones of Ogasawara National Park; parts of the former island as national forestland under Forestry Agency jurisdiction; access restricted to academic research with Ministry of the Environment authorisation; and the July 2018 aerial laser survey and revised charts issued 31 May 2019
12. UNESCO World Heritage Centre — Ogasawara Islands. Inscription in 2011 under criterion (ix), a property of 7,939 ha comprising 6,358 ha terrestrial and 1,581 ha marine, and the explicit inclusion of the isolated Nishinoshima Island as one of the five components
13. JAMSTEC — press release on arc crustal thickness and magma type (September 2016). The finding that thin crust of 10–20 km produces andesitic magmas while crust of about 35 km produces basaltic lavas; that Nishinoshima's erupted lavas are all andesitic with compositions similar to continental crust; and the argument that continents form in ocean areas
14. Frontiers in Earth Science — submarine deposits and magma mixing at Nishinoshima (2023). The crust beneath Nishinoshima at about 21 km thick and the volcano as one of the closest arc volcanoes to the mantle on Earth; 2020 products ranging from basalt to dacite; petrographic evidence of basalt-andesite mingling within the crust; and the inference about continental crust accumulation being greatest when crust was thin
15. NASA Earth Observatory — Nishinoshima Belches Ash and Lava. The southern shore growing at least 150 m between 19 June and 3 July 2020; the plume at 4,700 m on 3 July and ash detected at 8,300 m on 4 July, the highest since the volcano broke the water line in 2013; volcanic bombs thrown 2.5 km; and the TROPOMI sulphur dioxide plume
16. Journal of Plant Research — Origin of the Eleusine indica population on Nishinoshima (2026). All 25 sampled individuals sharing a single chloroplast haplotype, indicating founding by one or very few seeds; closest relationship to Ogasawara populations 130 km away, then Okinawa, then Indonesia; brown booby dispersal of the 1–2 mm seeds; and the burial of the roughly 0.5 ha population by ash and lava in the 2020 eruption
17. Terrestrial biota of Nishinoshima Island, the Ogasawara Islands, in 2021 (via CORE). The 2021 unmanned-aircraft survey finding the entire island covered by lava and ash with no vegetation established; brown and masked boobies, brown noddy, sooty tern, great crested tern and acoustically detected wedge-tailed shearwaters; fly pupae and plant seeds in a decomposing booby; and the suggestion that the island may be an ecological trap with very low breeding success
18. Ministry of the Environment, Japan — Ogasawara National Park. The park's coverage of the Chichi-jima, Muko-jima and Haha-jima groups plus Nishinoshima and Kita-Io-to, and confirmation that Nishinoshima falls under the Ogasawara Ranger Office's jurisdiction
19. Phys.org — Scientists trace origins of now extinct plant population from volcanically active Nishinoshima (September 2025). Independent reporting of the Eleusine indica result and the destruction of the population by the 2019–2020 eruption
20. GeoNames — Chichijima. Coordinates 27°4'8″N, 142°12'50″E for the nearest inhabited island, population about 2,000
21. GeoNames — Hahajima. Coordinates 26°40'6″N, 142°9'14″E for the second inhabited island of the Ogasawara group, and Hahajima harbour at 26°41'40″N, 142°9'10″E

Official and scientific bodies are the authority for safety, regulatory and scientific claims. Commercial operators are used only for practical detail such as tour length, meeting points and indicative pricing — never for a safety or scientific statement.