Donnerstag, Dez 20, 2012
Plume activity at the Iodake summit crater has remained at relatively low levels since the middle of 2009, and white plumes rose to a heights of up to 400 m above the crater rim during the reporting period. Weak volcanic glows were recorded at night with a high-sensitivity camera on November 6th and 22nd to 24th. ... [mehr]
Kikai Vulkan Ausbrüche
caldera 704 m / 2,310 ft
Ryukyu-Inseln, Japan, 30.79°N / 130.31°E
Eruption-Liste: 2004, 2003, 2002, 2000-01, 2000, 1998-99, 1997, 1988, 1934-35, 1914 (?)
radiocarbon / tephrochronology dated: 1430 ± 75 years, 1340 ± 30, 1030 ± 40, 1010 ± 40, 750 AD (?), 390 AD ± 100, 280 BC ± 75, 1090 BC ± 100, 1830 BC ± 75, 2450 BC ± 1000, 3250 BC ± 75, 3250 BC ± 75
around 4350 BC: VEI 7 caldera-forming eruption, one of the largest on earth in 10,000 years, producing the Akahoya tephra
The height of ash plumes never exceeded 2-3 km and the eruption caused no damage, only minor ash fall in nearby areas.
Residents of Tokara-Iwo-Jima saw ash eruptions in August and October 1998.
Residents did not feel any seismic activity preceding the eruption. A high-temperature fumaraole at the summit was measured 788°C, more or less unchanged since the last survey in 1985.
Source: GVP monthly reports
The eruption started from vents at a water depth of 200-300 m. "Smoke" and floating pumice were seen in September 1934 and detonations could be heard. By November, a new island started to appear, but was destroyed by explosions on 30 December 1934.
A second island formed in January 1935, reaching 300 m length, 150 width and a height of 20 m when measured on 20 January. It had a crater of 50 m diameter and a viscous lava flow was observed on the western side. A 3rd, smaller island was born on 20 February. Its activity was surtseyan, frequent phreatomagmatic eruptions at intervals of less than a few minutes, building up a pyroclastic cone. When observed on 26 March, it was 22-23 m high. The other island had entered a magmatic phase and a lava dome had appeared reaching 50-60 m height.
- Peter Hedervari (1986) "CATALOG OF SUBMARINE VOLCANOES AND HYDROLOGICAL PHENOMENA ASSOCIATED WITH VOLCANIC EVENTS", World Data Center A for Solid Earth Geophysics, Report SE-42, Georgiana Observatory, Budapest
- Kano, K. (2003) "Subaqueous Pumice Eruptions and Their Products: A Review", in White et al (eds.) "Explosive Subaqueous Volcanism", American Geophysical Union monograph 140, pp 231-244
The eruption produced massive rhyolithic pyroclastic flows that traveled across the sea for 100 km and reached southern Kyushu. Ash layers from this eruption are found all over Japan until the northernmost island Hokkaido and form an important geologic marker.
The eruption devastated southern and central Kyushu, which afterwards remained uninhabited for several centuries. The present-day caldera resulted at least partly from collapse after the eruption.