Very-Long-Period Seismic Signals and Caldera Formation at Miyake Island, Japan

Kumagai, Hiroyuki; Ohminato, Takao; Nakano, Masataka; Ooi, Masahiro; Kubo, Atsuki; Inoue, Hiroshi; Oikawa, Jun

doi:10.1126/science.1062136

Cited by 167 publications

(213 citation statements)

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“…Fukuyama et al (2001) analyzed stress fields due to 2000 eruption of the Usu volcano and swarm activity associated to 2000 eruption of Miyakejima volcano. Kumagai et al (2001) developed a caldera formation model associated to the volcanic activity of Miyakejima in 2000. Kubo et al (2002) analyzed maximum horizontal stress directions in and around Japan and local stress field in the focal zone of the western Tottori earthquake of 2000 (M7.3).…”

Section: Archive and Distribution Of F-net Datamentioning

confidence: 99%

Recent progress of seismic observation networks in Japan —Hi-net, F-net, K-NET and KiK-net—

et al. 2014

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After the disastrous 1995 Kobe earthquake, a new national project has started to drastically improve seismic observation system in Japan. A large number of strong-motion, high-sensitivity, and broadband seismographs were installed to construct dense and uniform networks covering the whole of Japan. The new high-sensitivity seismograph network consisting of 696 stations is called Hi-net, while the broadband seismograph network consisting of 71 stations is called F-net. At most of Hi-net stations strong-motion seismographs are also equipped both at depth and the ground surface. The network of these 659 stations with an uphole/downhole pair of strong-motion seismographs is called KiK-net, while another network consisting of 1034 strong-motion seismographs installed at the ground surface is called K-NET. Here, all the station numbers are as of April 2003. High-sensitivity data from Hi-net and pre-existing seismic networks operated by various institutions have been transmitted to and processed by the Japan Meteorological Agency since October 1997 to monitor the seismic activity in and around Japan. The same data are shared to university group in real time using satellite communication for their research work. The data are also archived at the National Research Institute for Earth Science and Disaster Prevention and stored in their database system for public use under a fully open policy.

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Section: Archive and Distribution Of F-net Datamentioning

confidence: 99%

Recent progress of seismic observation networks in Japan —Hi-net, F-net, K-NET and KiK-net—

et al. 2014

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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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“…The existence of a deep-seated basaltic magma chamber is suggested by the presence of the inflation source at around 9.5 km below sea level prior to the eruption (Nishimura et al, 2001). The existence of a shallow magma chamber at ∼3-5 km below sea level is suggested by the position of the deflation source during the 2000 eruption (Nishimura et al, 2001), the source depth of the verylong-period seismic signal (Kumagai et al, 2001; Kobayashi et al, 2009), and the location of the dike injection at the initial stage of eruption (Ueda et al, 2005;Irwan et al, 2006). Source analysis of the very-long-period seismic signal and tilt change reveals the existence of a vertically aligned and NE-SW elongated ellipsoidal magma chamber at around 2.6 km beneath the south flank of the edifice (Munekane et al, 2016).…”

Section: Discussionmentioning

confidence: 98%

Orientation of the Eruption Fissures Controlled by a Shallow Magma Chamber in Miyakejima

Geshi

Oikawa

2016

Front. Earth Sci.

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Orientation of the eruption fissures and composition of the lavas of the Miyakejima volcano is indicative of the competitive processes of the regional tectonic stress and the local stress generated by the activity of a magma plumbing system beneath the volcano. We examined the distributions and magmatic compositions of 23 fissures that formed within the last 2800 years, based on a field survey and a new dataset of 14 C ages. The dominant orientation of the eruption fissures in the central portion of the volcano was found to be NE-SW, which is perpendicular to the direction of regional maximum horizontal compressive stress (σ Hmax ). Magmas that show evidence of mixing between basaltic and andesitic compositions erupted mainly from the eruption fissures with a higher offset angle from the regional σ Hmax direction. The presence of a dike pattern perpendicular to the direction of maximum compression σ Hmax is an unusual and uncommon feature in volcanoes. Here we investigate the conditions possibly controlling this unexpected dike pattern. The distribution and magmatic compositions of the eruption fissures in Miyakejima volcano highlight the tectonic influence of shallow magma chamber on the development of feeder dikes in a composite volcano. The presence of a shallow dike-shaped magma chamber controls the eccentric distribution of the eruption fissures perpendicular to the present direction of σ Hmax . The injection of basaltic magma into the shallow andesitic magma chamber caused the temporal rise of internal magmatic pressure in the shallow magma chamber which elongates in NE-SW direction. Dikes extending from the andesitic magma chamber intrude along the local stress field which is generated by the internal excess pressure of the andesitic magma chamber. As the result, the eruption fissures trend parallel to the elongation direction of the shallow magma chamber. Some basaltic dikes from the deep-seated magma chamber reach the ground surface without intersection with the andesitic magma chamber. These basaltic dikes develop parallel to the regional compressive stress in NW-SE direction. The patterns of the eruption fissures can be modified in the future as was observed in the case of the destruction of the shallow magma chamber during the 2000 AD eruption.

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Very-Long-Period Seismic Signals and Caldera Formation at Miyake Island, Japan

Cited by 167 publications

References 3 publications

Recent progress of seismic observation networks in Japan —Hi-net, F-net, K-NET and KiK-net—

Recent progress of seismic observation networks in Japan —Hi-net, F-net, K-NET and KiK-net—

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

Orientation of the Eruption Fissures Controlled by a Shallow Magma Chamber in Miyakejima

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