Mechanism of Phreatic Eruptions at Aso Volcano Inferred from Near-Field Broadband Seismic Observations

Kaneshima, S.; Kawakatsu, Hitoshi; Matsubayashi, H.; Sudo, Y.; Tsutsui, T.; Ohminato, T.; Ito, H.; Uhira, K.; Yamasato, H.; Oikawa, J.; Takeo, M.; Iidaka, T.

doi:10.1126/science.273.5275.643

Cited by 35 publications

(60 citation statements)

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“…Hence, the source is not a double-couple, but it may more likely be isotropic, as for similar wavelength tremors already reported on Aso [Kaneshima et al, 1996;Legrand et al, 2000]. This has been our main hypothesis in order to emphasize that the polarization direction points towards the source (see Legrand et al [2000] for a detailed explanation).…”

Section: Legrand Et Al: Very Long Period Tremors At Ambrym Volcano Lmentioning

confidence: 58%

“…Whereas the occidental part of the edifice is the centre of an open plumbing system shown by two active lava lakes, the part of the volcano below the eastern part of the caldera is the site of the most energetic tremors in a close system. Thus, a first conclusion is that important VLPTs tremors may also be generated within a volcanic close system, as observed in only few cases [e.g., Kaneshima et al, 1996].…”

Section: Interpretation Of the Signals In The Volcanologic Context Ofmentioning

confidence: 99%

“…[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%

“…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. VLPTs of 20s, 11 -12s and 7s have also been recorded on Erebus, Antarctica [Rowe et al, 1998;Aster et al, 2003] as well as events with periods up to 20s on Stromboli, Italy [Chouet et al, 1999].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Legrand Et Al: Very Long Period Tremors At Ambrym Volcano Lmentioning

confidence: 58%

Section: Interpretation Of the Signals In The Volcanologic Context Ofmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…[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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Sudden changes in the amplitude‐frequency distribution of long‐period tremors at Aso volcano, southwest Japan

Sandanbata

Obara

Maeda

et al. 2015

Geophysical Research Letters

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We observed the activity of long‐period tremors (LPTs) with a period of ~15 s at Aso volcano, Japan, during a 3 year period including the 2014 eruptions. The number of LPTs detected systematically increased 3 months before the Strombolian eruptions. LPT activity can be divided into five stages based on rapid changes in the maximum LPT amplitude. The amplitude‐frequency relation follows an exponential distribution during each stage before the Strombolian eruptions, with different characteristic amplitudes for each stage, indicating that the scale of the source property changed in stages. However, during a stage that persisted for 6 days after the onset of Strombolian activity, the amplitude‐frequency relation temporarily followed a power law distribution, indicating that the LPT source process no longer had a characteristic scale. In the last stage, the amplitude‐frequency relation returned to an exponential distribution. We therefore conclude that the physical source of volcanic LPTs changed during the eruption period.

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Mechanism of Phreatic Eruptions at Aso Volcano Inferred from Near-Field Broadband Seismic Observations

Cited by 35 publications

References 0 publications

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

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

Sudden changes in the amplitude‐frequency distribution of long‐period tremors at Aso volcano, southwest Japan

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