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Mass budget of the magma flow in the 2000 volcano-seismic activity at Izu-islands, Japan

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Title: Mass budget of the magma flow in the 2000 volcano-seismic activity at Izu-islands, Japan
Authors: Furuya, M. Browse this author →KAKEN DB
Okubo, S. Browse this author
Kimata, F. Browse this author
Miyajima, R. Browse this author
Meilano, I. Browse this author
Sun, W. Browse this author
Tanaka, Y. Browse this author
Miyazaki, T. Browse this author
Keywords: Absolute gravity
Issue Date: Aug-2003
Publisher: TERRAPUB
Journal Title: Earth, Planets and Space
Volume: 55
Issue: 7
Start Page: 375
End Page: 385
Abstract: Eruptive and caldera-forming activity at Miyakejima volcano island, Japan, commenced on 26 June 2000 was accompanied by more than 40 day of seismic swarms and significant crustal deformation in the nearby islands and sea region besides those at Miyakejima itself. The migration of the hypocenters in the early stage suggests that they were triggered by magma intrusion from Miyakejima. However, it remains uncertain whether the long-lasting seismic swarms and ground displacements in the northern Izu-islands were totally maintained by the magma flow from Miyakejima, because another magma source nearby Kozushima was suggested previously, which is 40 km north-west of Miyakejima, based upon anomalous ground displacements. Here we report the detection of associated changes with the 2000 activity in both absolute gravity and elevation at Kozushima as well as those at Miyakejima. Combining these data with horizontal GPS displacements, we extend the analysis of Nishimura et al. (2001) and construct an optimum source model, so that we can account for the observed changes in geodetic data and determine the mass budget of the magma flow. The total mass of the newly intruded dike offshore of Miyakejima and nearby Kozushima turned out to be 130% or greater than the lost mass at Miyakejima. As long as there are no other source elements, another magma reservoir near Kozushima is required and is suggested to have been activated, causing the seismic swarms and crustal deformation. We may speculate as a phenomenology that the rapid lateral magma flow from Miyakejima in the very beginning of the unrest awakened a dormant reservoir offshore of Miyakejima and Kozushima.
Type: article
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 古屋 正人

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