Broadband seismic observation at the Sakurajima Volcano, Japan

Kawakatsu, Hitoshi; Ohminato, Takao; Ito, Hisao; Kuwahara, Yasuto; Kato, Takashi; Tsuruga, Kayoko; Honda, Sawao; Yomogida, Kiyoshi

doi:10.1029/92gl01964

Cited by 62 publications

(23 citation statements)

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“…Recent broadband seismic observations on active volcanoes have revealed the existence of VLP signals characterized by impulsive signatures or sustained oscilla-tions with periods longer than a few seconds (14)(15)(16)(17)(18)(19)(20)(21), which may be primarily linked to fluid-transport processes in magmatic and hydrothermal systems. In comparison with these signals, the VLP signals observed at Hachijo Island are of particular importance because the characteristic properties of the resonator system can be determined from the frequencies and Q factors of the decaying oscillations, as demonstrated by this study.…”

Section: Magmatic Dike Resonances Inferred From Very-long-period Seismentioning

confidence: 99%

Magmatic Dike Resonances Inferred from Very-Long-Period Seismic Signals

Kumagai

Miyakawa

Negishi

et al. 2003

Science

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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.

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Section: Magmatic Dike Resonances Inferred From Very-long-period Seismentioning

confidence: 99%

Magmatic Dike Resonances Inferred from Very-Long-Period Seismic Signals

Kumagai

Miyakawa

Negishi

et al. 2003

Science

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“…[2] Since about ten years, broadband seismometers (0.01 to 120 s) have been largely used to record volcanic tremors, volcanic earthquakes, phreatic or magmatic explosions [e.g., Kawakatsu et al, 1992;Chouet et al, 1994;Neuberg et al, 1994;Kaneshima et al, 1996;Rowe et al, 1998]. Nevertheless, Very Long Period signals (hereafter noted VLPTs) have been observed in only a few cases, as on Aso, (Japan), where Kaneshima et al [1996] reported tremors with periods of 10-15s.…”

Section: Introductionmentioning

confidence: 99%

Interpretation of very long period tremors at Ambrym volcano, Vanuatu, as quasi‐static displacement field related to two distinct magmatic sources

Legrand

Rouland²,

Frogneux³

et al. 2005

Geophysical Research Letters

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A 3‐component broadband seismometer (STS‐2) has been deployed on the SW slope of Ambrym, Vanuatu, a large‐caldera volcano with two persistent lava lakes from July to November 2000. Well‐polarized Very Long Period Tremors (18–22s; VLPTs) occurred quite continuously, whereas other seismic signal with periods of 9s, 6–7s, 5s, 2.3–2.7s, 1.95s and 1s were intermittent. VLPTs signals show two clearly distinct directions pointing towards the caldera. Polarization orientations suggest two sources: the first one, and the most active, fits with the zone from which silicic lava flows erupted in 1986, in the central‐to‐eastern part of the caldera. The second one corresponds to the active zone formed by the complex Marum volcanic center and the Benbow cone, in the western part of the depression structure. The depths are estimated between 2.7–2.9 km with respect to sea level. VLPTs are interpreted as the quasi static‐displacement field of two nondestructive sources. They indicate the persistent continuing magmatic activity beneath the eastern floor of the caldera, although no volcanic activity is observed in this area, and the more obvious, but less active, corresponding to the lava lakes. These data also corroborate the complex internal structure of the Ambrym caldera, suggested by geological data and bimodal magmatism (basaltic, ∼50% SiO2, and silicic, ∼60% SiO2).

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“…[9] Where VLP earthquakes have been observed [Kawakatsu et al, 1992;Kawakatsu et al, 1994;Neuberg et al, 1994;Kaneshima et al, 1996;Ohminato et al, 1998;Arciniega-Ceballos et al, 1999;Legrand et al, 2000;Nishimura et al, 2000;Rowe et al, 2000;Kumagai et al, 2001;Almendros et al, 2002;Hidayat et al, 2002;Hill et al, 2002;Aster et al, 2003;Chouet et al, 2003Chouet et al, , 2005 they are typically attributed to fluid-rock interactions, as with LP events. However, instead of resonance in a fluid-filled crack, VLP events may result from longer-term inertial volume changes in fluid conduits.…”

Section: Introductionmentioning

confidence: 99%

Eruption dynamics at Mount St. Helens imaged from broadband seismic waveforms: Interaction of the shallow magmatic and hydrothermal systems

2008

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[1] The current eruption at Mount St. Helens is characterized by dome building and shallow, repetitive, long-period (LP) earthquakes. Waveform cross-correlation reveals remarkable similarity for a majority of the earthquakes over periods of several weeks. Stacked spectra of these events display multiple peaks between 0.5 and 2 Hz that are common to most stations. Lower-amplitude very-long-period (VLP) events commonly accompany the LP events. We model the source mechanisms of LP and VLP events in the 0.5-4 s and 8-40 s bands, respectively, using data recorded in July 2005 with a 19-station temporary broadband network. The source mechanism of the LP events includes: 1) a volumetric component modeled as resonance of a gently NNW-dipping, steam-filled crack located directly beneath the actively extruding part of the new dome and within 100 m of the crater floor and 2) a vertical single force attributed to movement of the overlying dome. The VLP source, which also includes volumetric and single-force components, is 250 m deeper and NNW of the LP source, at the SW edge of the 1980s lava dome. The volumetric component points to the compression and expansion of a shallow, magmafilled sill, which is subparallel to the hydrothermal crack imaged at the LP source, coupled with a smaller component of expansion and compression of a dike. The single-force components are due to mass advection in the magma conduit. The location, geometry and timing of the sources suggest the VLP and LP events are caused by perturbations of a common crack system.

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Broadband seismic observation at the Sakurajima Volcano, Japan

Cited by 62 publications

References 0 publications

Magmatic Dike Resonances Inferred from Very-Long-Period Seismic Signals

Magmatic Dike Resonances Inferred from Very-Long-Period Seismic Signals

Interpretation of very long period tremors at Ambrym volcano, Vanuatu, as quasi‐static displacement field related to two distinct magmatic sources

Eruption dynamics at Mount St. Helens imaged from broadband seismic waveforms: Interaction of the shallow magmatic and hydrothermal systems

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