is a group of

islets An islet ( ) is generally a small island. Definitions vary, and are not precise, but some suggest that an islet is a very small, often unnamed, island with little or no vegetation to support human habitation. It may be made of rock, sand and ...

in the

Sea of Japan The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it ...

about west of the

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

ese main island of

Honshu , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...

. It is administered as part of the town of

Fukaura is a town located in Aomori Prefecture, Japan. , the town had an estimated population of 7,268 in 3553 households, and a population density of 15 persons per km2. The total area of the town is . Geography Fukaura is in Nishitsugaru Distric ...

Aomori Prefecture is a Prefectures of Japan, prefecture of Japan in the Tōhoku region. The prefecture's capital, largest city, and namesake is the city of Aomori (city), Aomori. Aomori is the northernmost prefecture on Japan's main island, Honshu, and is border ...

and is the prefecture's westernmost point. The islets are the peaks of a

submarine volcano Submarine volcanoes are underwater vents or fissures in the Earth's surface from which magma can erupt. Many submarine volcanoes are located near areas of tectonic plate formation, known as mid-ocean ridges. The volcanoes at mid-ocean ridges ...

Geography

Kyūroku-jima is located west of Honshu, and is Aomori Prefecture's westernmost point. The islets are the peaks of a submarine volcano. The islets are surrounded by rocky reefs that are difficult to navigate, but the largest island has a

quay A wharf ( or wharfs), quay ( , also ), staith, or staithe is a structure on the shore of a harbour or on the bank of a river or canal where ships may dock to load and unload cargo or passengers. Such a structure includes one or more Berth (mo ...

built on to it. Due to this difficulty, the

Japan Coast Guard The is the coast guard responsible for the protection of the Geography of Japan#Composition, topography and geography, coastline of Japan under the oversight of the Ministry of Land, Infrastructure, Transport and Tourism. It consists of about ...

only visits the islands once a year to do inspections on their lighthouse.

Geology

The volcano that makes up Kyūroku-jima formed about 3.32 million years ago. The rock that is above the ocean surface is made up of dark-colored alkali basalt and a yellow

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock co ...

, each of which are distinctly visible to visitors. The islets of Kurokushima are the peaks of a horseshoe-shaped caldera that rises about from the surrounding seafloor. It is comparable to nearby

Mount Iwaki is a stratovolcano located in western Aomori Prefecture, Tohoku, Japan. It is also referred to as and less frequently, due to its similar shape to Mount Fuji. With a summit elevation of and a Topographic prominence, prominence of it is th ...

, which also has a prominence of around relative to

Shirakami-Sanchi file:Shirakami Mountains Relief Map, SRTM-1 (with UNESCO World Heritage Site).jpg, 270px, Shirakami Mountains Relief Map (with UNESCO World Heritage Site) is a UNESCO World Heritage Site in the Tōhoku region of northern Honshū, Japan. This mou ...

History

Kyūroku-jima was charted in 1786 by merchants, though the area had been known as a fishing ground since the sixteenth century when a fisherman named Kyūroku crashed on the islands, giving them their name. The islets were first observed by Europeans in 1855, when the crew of spotted them covered in seals. The crew named the islets the Bittern Rocks, a name that stuck with Western sources at least until the beginning of the twentieth century. Because of the abundance of

Okhotsk atka mackerel The Okhotsk Atka mackerel (''Pleurogrammus azonus''), also known as the Arabesque greenling, is a mackerel-like species in the family Hexagrammidae. It is commonly known as ''hokke'' (法華) in Japan and ''imyeonsu'' in Korean. The primary popul ...

abalone Abalone ( or ; via Spanish , from Rumsen language, Rumsen ''aulón'') is a common name for any small to very large marine life, marine gastropod mollusc in the family (biology), family Haliotidae, which once contained six genera but now cont ...

, and

kelp Kelps are large brown algae or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...

, the jurisdiction of the islets were disputed between the prefectures of Aomori and Akita until it was added to Aomori in 1953 and Akita received a common right of use. On 20 October 1959, a unmanned lighthouse began operation, the lighting of which has a range of .

Transportation

The only way the islets can be accessed is by chartering a fishing boat. It takes about two hours to reach the islands from Fukaura.

References

{{reflist Fukaura, Aomori Islands of Aomori Prefecture Islands of the Sea of Japan Pliocene volcanoes Submarine calderas Uninhabited islands of Japan Volcanoes of Aomori Prefecture