Mount Aso alert level raised to 2

Mount Aso alert level raised to 2

The Meteorological Agency on Monday raised the volcanic alert level for Mount Aso from 1 to 2, prompting local authorities in Kumamoto Prefecture to ban entry to areas within 1 km of the crater of Mount Naka, one of five peaks in the active volcano's central cone group.


The alert includes a warning for rocks ejected from Mount Naka in the off-limits areas.


The move came after the mountain belched a small amount of volcanic ash Friday and experienced a small eruption Sunday.


On Monday, a small eruption and a 500-meter-high column of volcanic smoke were observed at around 10 a.m. (TheJapanTimes)



AbbreviationKeywordVolcanoIssued at
Near-crater warningLevel 3(Do not approach the volcano)Kirishimayama(Shinmoedake)17:00 JST, 22 March 2011
Near-crater warningLevel 3(Do not approach the volcano)Sakurajima22:35 JST, 13 October 2010
Near-crater warningLevel 2(Do not approach the crater)Asosan11:00 JST, 16 May 2011
Near-crater warningLevel 2(Do not approach the crater)Miyakejima10:00 JST, 31 March 2008
Near-crater warningLevel 2(Do not approach the crater)Suwanosejima10:06 JST, 01 December 2007
Near-crater warningLevel 2(Do not approach the crater)Satsuma-Iojima10:04 JST, 01 December 2007
Near-crater warningWarnings around the craterIoto10:01 JST, 01 December 2007
Warning(sea area)Warnings for sea areas in the vicinity of a volcanoFukutoku-Oka-no-Ba10:02 JST, 01 December 2007

AbbreviationKeywordVolcanoIssued at
Near-crater warningLevel 3(Do not approach the volcano)Kirishimayama(Shinmoedake)17:00 JST, 22 March 2011
Near-crater warningLevel 3(Do not approach the volcano)Sakurajima22:35 JST, 13 October 2010
Near-crater warningLevel 2(Do not approach the crater)Asosan11:00 JST, 16 May 2011
Near-crater warningLevel 2(Do not approach the crater)Suwanosejima10:06 JST, 01 December 2007
Near-crater warningLevel 2(Do not approach the crater)Satsuma-Iojima10:04 JST, 01 December 2007
 


Mount Aso (阿蘇山 Aso-san) is the largest active volcano in Japan, and is among the largest in the world. It stands in Aso Kujū National Park in Kumamoto Prefecture, on the island of Kyūshū. Its peak is 1592 m above sea level. Aso has one of the largestcaldera in the world (25 km north-south and 18 km east-west).  The caldera has a circumference of around 120 km (75 miles), although sources vary on the exact distance.

The central cone group of Aso consists of five peaks: Mt. Neko, Mt. Taka, Mt. Naka, Mt. Eboshi, and Mt. Kishima. The highest point is the summit of Mt. Taka, at 1592 m above sea level. The crater of Mt. Naka, the west side of which is accessible by road, contains an active volcano which continuously emits smoke and has occasional eruptions. Only the northernmost crater (the first crater) has been active for the last 70 years—1974, 1979, 1984–1985, 1989-1991, 2009, and 2011.

The present Aso caldera formed as a result of four huge caldera eruptions occurring over a range of 90,000–300,000 years ago. The caldera, one of the largest in the world, contains the city of Aso as well as Aso Takamori-cho and South Aso-mura. The sommaenclosing the caldera extends about 18 km east to west and about 25 km north to south. Viewpoints from the somma overlooking the caldera are perched upon lava formed before the volcanic activity which created the present caldera.

Ejecta from the huge caldera eruption 90,800 years ago covers more than 600 km³ and roughly equals the volume of Mt. Fuji; it is presumed that the pyroclastic flow plateau covered half of Kyūshū

 

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