:Kyūroku-jima
{{short description|Islets of Aomori Prefecture, Japan}}
{{Infobox Islands
| name = Kyūroku-jima
| image_name = Kyuroku-jima island aerial photograph.JPG
| native_name = {{langx|ja|久六島}}
| native_name_link =
| image_caption = Aerial photograph of Kyūroku-jima
| image_size =
| pushpin_map = Japan
| map_alt = Location in Japan
| pushpin_label = Kyūroku-jima
| pushpin_label_position = {{Coord|40|32|0|N|139|29|58|E|type:isle|display=inline,title}}
| pushpin_map_alt =
| pushpin_relief =
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| map_custom =
| nickname =
| location = Sea of Japan
| coordinates = {{Coord|40|32|0|N|139|29|58|E|type:isle}}
| archipelago =
| total_islands =
| major_islands =
| area_km2 =
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| highest_mount =
| elevation_m = 4.7
| country = Japan
| country_admin_divisions_title = Prefecture
| country_admin_divisions = Aomori Prefecture
| country_admin_divisions_title_1 = Town
| country_admin_divisions_1 = Fukaura
| population = 0
| population_as_of =
| density_km2 = 0
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}}
{{nihongo|Kyūroku-jima|久六島}} is a group of islets in the Sea of Japan about {{convert|30|km|mi|sp=us}} west of the Japanese main island of Honshu. It is administered as part of the town of Fukaura in Aomori Prefecture and is the prefecture's westernmost point. The islets are the peaks of a submarine volcano.
Geography
Kyūroku-jima is located {{convert|30|km|mi|sp=us}} west of Honshu, and is Aomori Prefecture's westernmost point.{{cite web|title=場所・気候|trans-title=Place/climate|url=https://www.pref.aomori.lg.jp/kids/02_climate.html|language=ja|publisher=Aomori Prefecture Government|date=20 May 2020|accessdate=12 July 2020}} The islets are the peaks of a submarine volcano.{{cite web|title=About : 久六島西方海底火山 ／ Submarine Volcano West of Kyuroku Jima|url=https://www.mirko.jp/LODSI/demo_SSL/demoS04/?404|publisher=公共オープンデータ|accessdate=12 July 2020}}
The islets are surrounded by rocky reefs that are difficult to navigate, but the largest island has a quay built on to it. Due to this difficulty, the Japan Coast Guard only visits the islands once a year to do inspections on their lighthouse.{{cite news|title=日本の領海広げる久六島ルポ 地震で小さく|trans-title=Report on Kyūroku-jima which spreads Japan's territorial waters, shrank in earthquake|url=https://www.asahi.com/articles/ASG7B0BFCG79UBNB014.html|archive-url=https://web.archive.org/web/20140728155602/https://www.asahi.com/articles/ASG7B0BFCG79UBNB014.html|language=ja|newspaper=The Asahi Shimbun|archive-date=28 July 2014|date=11 July 2014|accessdate=12 July 2020}}
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, each of which are distinctly visible to visitors. The islets of Kurokushima are the peaks of a horseshoe-shaped caldera that rises about {{convert|1,000|m|ft|sp=us}} from the surrounding seafloor. It is comparable to nearby Mount Iwaki, which also has a prominence of around {{convert|1,000|m|ft|sp=us}} relative to Shirakami-Sanchi.{{cite journal|author1=Takaaki Fukudome|author2=Takeyoshi Yoshida|author3=Keisuke Nagao|author4=Tetsumaru Itaya|author5=Seiji Tanoue|title=Pliocene alkali basalt from Kyuroku-shima Island, northeast of Japan Sea|url=https://www.jstage.jst.go.jp/article/ganko1988/85/1/85_1_10/_pdf/-char/ja|language=ja|date=1990|accessdate=13 July 2020|doi=10.2465/ganko.85.10|journal=Journal of Mineralogy, Petrology, and Economic Geology|volume=85|issue=1|pages=10–18|doi-access=free}}
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.{{cite web|title=久六島|trans-title=Kyūroku-jima|url=https://kotobank.jp/word/%E4%B9%85%E5%85%AD%E5%B3%B6-52244|language=ja|publisher=Kotobank|accessdate=12 July 2020}} The islets were first observed by Europeans in 1855, when the crew of {{HMS|Bittern}} 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.{{cite book|author=David Starr Jordan|title=The Fur Seals and Fur-Seal Islands of North Pacific Ocean|url=https://books.google.com/books?id=QxLOAAAAMAAJ&q=bittern+rocks+sea+of+japan+1855&pg=PA239|location=Washington|publisher=Government Printing Office|page=239|date=1898|accessdate=12 July 2020}}
Because of the abundance of Okhotsk atka mackerel, abalone, and kelp, 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 {{convert|20|m|ft|adj=mid|-high|sp=us}} unmanned lighthouse began operation, the lighting of which has a range of {{convert|7.5|km|mi|sp=us}}.{{cite web|title=久六島灯台|trans-title=Kyūroku-jima lighthouse|url=https://www.kaiho.mlit.go.jp/02kanku/aomori/new/aomorihoanbu/kyurokushima.htm|publisher=MLITT Japan|language=ja|accessdate=12 July 2020}}