Miyake-jima
Miyake- jima (Japanese三 宅 岛) is a volcanic island in the Pacific Ocean. It belongs geographically to the Japanese Izu Islands and counts as the entire island group, administratively to the Prefecture Tokyo.
Geography
Miyake- jima is located about 180 km south of Tokyo and 22 km north of the neighboring island of Mikura -jima, with which they the sub-prefecture Miyake (三 宅 支 庁, Miyake- shicho ) forms. The island is about 11 km long, up to 8 km wide and has an area of 55.44 km ². It is to Izu - Oshima and Hachijo -jima, the third largest of the Izu Islands.
The community Miyake (三 宅村, -mura, even village) includes not only the island of Miyake- jima also, about 10 km west-southwest area, this small and uninhabited rock group Ōnohara -jima. In April 2009, the island had 2324 inhabitants. The population density is 42 inhabitants. / Km ². The island has several resorts along the coast. Capital ( seat of the municipality ) is Tsubota on the southeast coast.
Volcanism
As Miyake -jima volcano is part of the arc of the Izu, Bonin and Mariana Islands. In its substance, the structure of the volcano about 10,000 years ago was completed. From this period comes Kuwakidaira caldera with a diameter of 3.5 km in the center of the island. In its interior the Hatchodaira caldera was formed in an eruption about 2500 years ago with a diameter of 1.5 kilometers. Other outbreaks in which Basaltandesit was promoted, created inside the calderas of the volcanic layer Oyama, the highest point of the island. Before 2000, he had a height of 815 meters above the sea level.
Characteristic of the eruptions during the past 600 years were columns eruptions, where slag was ejected and lava leaked. If the columns ranged up to the area of the coast, there was phreatomagmatic explosions, which Maare, Tuffringe and explosion craters formed.
In the 20th century there were in 1940, 1962, 1983 and 2000 outbreaks. 11 people died in 1940. The former eruption took place just as the 1962 from columns in the northeast of the island. On 3 October 1983, a 4.5-km long column in the southwest of the island, shot from the fountains into the air opened. Were formed lava flows, one of which flowed to the south, reached the sea and there triggered phreatomagmatic explosions. Another lava flow turned westward and showered large parts of the village Ako, with around 400 houses were destroyed. The approximately 1400 inhabitants Akos were evacuated with boats and buses. Similar to the outbreak of Eldfells in Iceland in 1973 was an attempt to cool the lava with sea water to slow its further advance. The outbreak ended after ten hours.
- Satellite photographs of Miyake- jima
April 1, 2001
November 14, 2011
On 27 June 2000, there was approximately one kilometer west of Miyake- jima in a smaller submarine eruption. On the day before a series of earthquakes had been registered, their epicenters were shifting over several days to the northwest in the direction of the island Kōzu -shima. An earthquake on July 1 with a magnitude (MW) of 6.1 disbanded Kōzu -shima from a landslide, by which a man died. From July 8, a new caldera, which was formed in mid-August in the middle of Miyake- jima a diameter of 1.6 km and a depth of 450 meters had. As of 10 August, there were more phreatic and phreatomagmatic eruptions, the ash and lapilli promoted and sustained through the end of September in the new Caldera. During an outbreak on 18 August an eruption column rose over ten kilometers high. The series of earthquakes is interpreted as the emergence of Dykes, invaded from the magma chamber at Miyake- jima in the magma. Subsequently, the ceiling above the magma chamber collapsed, causing the caldera was formed.
End of August 2000, all 3,800 inhabitants of the island were evacuated, as it was feared that rains mobilize the ash deposits and trigger mudslides could. From September, the volcano emitted extraordinarily large amounts of sulfur dioxide ( SO2). The emissions reached in November 2000 with 80,000 tons per day peaked and declined until the end of 2004 to 2000-5000 tons per day. Despite continued high SO2 concentrations, the evacuation of residents in February 2005 has been terminated. The islanders were advised to carry respirators with it; Moreover, access restrictions in high risk areas were considered. For quick information of the population at elevated SO2 concentrations warning lights and loudspeakers were used. After 2000 there were several times, most recently in 2010, to smaller explosive eruptions in the caldera.
Fauna and Flora
Miyake- jima is located as part of the Izu Islands in the Fuji -Hakone -Izu National Park. The island has, in spite of human influences, as well as volcanic activity, a wide variety of species. It is worth mentioning occurring on only a few Izu Izu Islands Thrush (Turdus celaenops ).