Report on Miyakejima (Japan) — 24 July-30 July 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 July-30 July 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Miyakejima (Japan). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 24 July-30 July 2002. Smithsonian Institution and US Geological Survey.
34.094°N, 139.526°E; summit elev. 775 m
All times are local (unless otherwise noted)
The Air Force Weather Agency reported that a low-level steam-and-ash cloud from Miyake-jima was visible on satellite imagery on 26 July at 0713 and on 27 July at 0606. Around this time a continuous plume was visible at a height of 2.4-3 km a.s.l.
Geologic Background. The circular, 8-km-wide island of Miyakejima forms a low-angle stratovolcano that rises about 1100 m from the sea floor in the northern Izu Islands about 200 km SSW of Tokyo. The basaltic volcano is truncated by small summit calderas, one of which, 3.5 km wide, was formed during a major eruption about 2500 years ago. Parasitic craters and vents, including maars near the coast and radially oriented fissure vents, dot the flanks of the volcano. Frequent historical eruptions have occurred since 1085 CE at vents ranging from the summit to below sea level, causing much damage on this small populated island. After a three-century-long hiatus ending in 1469, activity has been dominated by flank fissure eruptions sometimes accompanied by minor summit eruptions. A 1.6-km-wide summit caldera was slowly formed by subsidence during an eruption in 2000; by October of that year the crater floor had dropped to only 230 m above sea level.
Source: US Air Force Weather Agency