, 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, Yakus ...
, usually classed with the
Ōsumi Islands, belonging to
Kagoshima Prefecture
is a prefecture of Japan located on the island of Kyushu and the Ryukyu Islands. Kagoshima Prefecture has a population of 1,599,779 (1 January 2020) and has a geographic area of 9,187 km2 (3,547 sq mi). Kagoshima Prefecture borders Kumamoto P ...
,
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
.
A deserted volcanic island, it is located just off the northern shore of
Iōjima,
Kagoshima
, abbreviated to , is the capital city of Kagoshima Prefecture, Japan. Located at the southwestern tip of the island of Kyushu, Kagoshima is the largest city in the prefecture by some margin. It has been nicknamed the "Naples of the Eastern wor ...
.
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 on ...
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
Caldera formation has been dated from about 95,000 years ago and has in ...
, a
stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
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 highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular vol ...
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 moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...
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
A desert island, deserted island, or uninhabited island, is an island, islet or atoll that is not permanently populated by humans. Uninhabited islands are often depicted in films or stories about shipwrecked people, and are also used as stereot ...
*
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 (often spelled water body) is any significant accumulation of water on the surface of Earth or another plane ...
References
External links
Map of Shōwa Iōjima, Kagoshimaby
Geographical Survey Institute
Kikai, Kyushu, Japanon Volcano World, Department of Geosciences at Oregon State University
{{DEFAULTSORT:Showa Iojima
New islands
Ōsumi Islands
Uninhabited islands of Japan
20th-century volcanic events
Islands of Kagoshima Prefecture