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Gigantic SO (sub 2) emission from Miyakejima Volcano, Japan, caused by caldera collapse

Kohei Kazahaya, Hiroshi Shinohara, Kozo Uto, Masanobu Odai, Yasuhiro Nakahori, Hirokazu Mori, Hideki Iino, Makoto Miyashita and Junichi Hirabayashi
Gigantic SO (sub 2) emission from Miyakejima Volcano, Japan, caused by caldera collapse
Geology (Boulder) (May 2004) 32 (5): 425-428


An extremely large amount of volcanic gas has been released since mid-August 2000 from the volcanic island of Miyakejima, Japan, after formation of a summit caldera of 1.6 km diameter. The volcanic gas emission was continuous with very little extrusive magma activity. Variation of the SO (sub 2) emission rate was monitored by repeated measurements with an airborne correlation spectrometer. In December 2000, the SO (sub 2) emission rate averaged for the month peaked at 54 kt/d, which is twice the global SO (sub 2) emission rate from nonerupting volcanoes evaluated before this activity. The SO (sub 2) emission rate gradually decreased, almost linearly when plotted on a log scale, to 7 kt/d by the end of 2002, and then remained constant until at least December 2003. The total SO (sub 2) emission amounts to 18 Mt, comparable to the emission of a large explosive eruption such as Pinatubo in 1991. A theoretical evaluation, based on the model of magma convection in a conduit, suggests that extremely large volcanic gas emissions can be caused by formation of a magma pathway with a slightly larger diameter than exists in common systems, because the magma-transport rate is proportional to the fourth power of the conduit radius. Because volcanic gas emissions were initiated by formation of a summit collapse caldera of 1.6 km diameter, the creation of a large magma-conduit system through fractures formed during caldera collapse is likely the underlying cause of the extremely large volcanic gas emissions from the volcano.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 32
Serial Issue: 5
Title: Gigantic SO (sub 2) emission from Miyakejima Volcano, Japan, caused by caldera collapse
Affiliation: Geological Survey of Japan, Institute of Advanced Science and Technology, Ibaraki, Japan
Pages: 425-428
Published: 200405
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 22
Accession Number: 2004-047841
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2004069
Illustration Description: illus. incl. sketch map
N34°04'60" - N34°10'00", E139°28'00" - E139°31'60"
Secondary Affiliation: Japan Meteorological Agency, JPN, JapanTokyo Institute of Technology, JPN, Japan
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200413
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