, also known as , is one of the
Satsunan Islands
The is a geopolitical name for a group of islands that forms the northern part of the Ryukyu Islands. The whole island group belongs to Kagoshima Prefecture, Japan.
Major islands
* Satsunan Islands
** Ōsumi Islands with:
*** Tanegashima, Yak ...
, usually classed with the
Ōsumi Islands
The is an archipelago in the Ryukyu Islands, Ryukyu Archipelago, and are the northernmost group of the Ryukyu Islands, The chain extends from the southern tip of Kyushu to Yakushima. Administratively, the group belongs within Kagoshima Prefecture ...
, belonging to
Kagoshima Prefecture
is a Prefectures of Japan, prefecture of Japan located on the island of Kyushu and the Ryukyu Islands. Kagoshima Prefecture has a population of 1,527,019 (1 February 2025) and has a geographic area of 9,187 Square kilometre, km2 (3,547 Square m ...
,
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 ...
.
A deserted volcanic island, it is located just off the northern shore of
Iōjima,
Kagoshima
, is the capital Cities of Japan, city of Kagoshima Prefecture, Japan. , the city had an estimated population of 583,966 in 285,992 households, and a population density of 1100 persons per km2. The total area of the city is .
Etymology
While the ...
.
Geography
Shōwa Iōjima is one of the Ōsumi islands, and is located north of
Iōjima. The island has an area of approximately with a coastline of in length. The island is an exposed
lava dome
In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...
associated with the submarine
Kikai Caldera
(alternatively Kikaiga-shima, Kikai Caldera Complex) is a massive, mostly submerged caldera up to in diameter in the Ōsumi Islands of Kagoshima Prefecture, Japan.
Geology
The Kikai Caldera Complex has twin ovoid caldera by in diameter. Yaha ...
, a
stratovolcano
A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...
rising from the ocean floor.
History
Shōwa Iōjima came into existence during an eruption in 1934. On September 12, 1934, earthquakes began, continuing for several days. On September 17, a plume of ash and smoke erupted from the ocean surface, and by September 20 an island of ash and
pumice
Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of extremely vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicula ...
began to form.
Lava flow
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
s were confirmed on November 25, and on December 7, the existence of a new island was confirmed. The volcanic peak on the island reached a height of about 30 meters by December 23, but on December 30, the island sank beneath sea level and disappeared.
However, the island reemerged on January 5 and on January 19 a strong eruption with black clouds of volcanic smoke, ash, lava flows and an acidic rain began, continuing for several weeks. On March 8, residents of neighboring Iōjima made the first landing on the new island. By April 1, all volcanic activity and earthquakes ceased. At that time, the size of Shōwa Iōjima was estimated to be . Subsequent erosion has reduced it to its present size.
See also
*
Desert island
An uninhabited island, desert island, or deserted island, is an island, islet or atoll which lacks permanent human population. Uninhabited islands are often depicted in films or stories about shipwrecked people, and are also used as stereotypes ...
*
List of islands
This is a list of the lists of islands in the world grouped by country, by continent, by body of water
A body of water or waterbody is any significant accumulation of water on the surface of Earth or another planet. The term most often refer ...
References
External links
Map of Shōwa Iōjima, Kagoshimaby
Geographical Survey Institute
The , or GSI, is the national institution responsible for surveying and mapping the national land of Japan. The former name of the organization from 1949 until March 2010 was Geographical Survey Institute; despite the rename, it retains the same ...
Kikai, Kyushu, Japanon Volcano World, Department of Geosciences at Oregon State University
{{DEFAULTSORT:Showa Iojima
Ōsumi Islands
Uninhabited islands of Japan
20th-century volcanic events
Islands of Kagoshima Prefecture