title: Magmatic dike resonances inferred from very-long-period seismic signals.
abstract: Very-long-period (VLP) signals showing simple decaying harmonic oscillations with periods near 10 seconds and lasting for about 300 seconds were observed in association with an earthquake swarm that occurred beneath Hachijo Island, Japan. Results from the source-mechanism analysis and waveform simulation based on a fluid-filled crack model consistently point to the resonance of a dike filled with a basaltic magma as the source of the VLP signals. Thus, VLP signals can be used to probe the state of the fluid and dynamic processes within a volcanic system.
authors.affiliation: National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Japan. kumagai@bosai.go.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kumagai
authors.forename: Koji
authors.initials: K
authors.lastname: Miyakawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Negishi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
authors.forename: Kazushige
authors.initials: K
authors.lastname: Obara
authors.forename: Daisuke
authors.initials: D
authors.lastname: Suetsugu