Updated on 2022/05/25

写真a

 
SUZUKI, Yuki
 
Affiliation
Faculty of Education and Integrated Arts and Sciences, School of Education
Job title
Associate Professor

Concurrent Post

  • Faculty of Science and Engineering   Graduate School of Creative Science and Engineering

Degree

  • 東京大学   博士(理学)

Research Experience

  • 2021.04
    -
    Now

    東京大学地震研究所 外来研究員

  • 2019.04
    -
    2021.03

    The University of Tokyo   Earthquake Research Institute

  • 2014.04
    -
    2019.03

    東京大学地震研究所 外来研究員

  • 2014.04
    -
    2017.03

    Waseda University   Faculty of Education and Integrated Arts and Sciences

Professional Memberships

  •  
     
     

    American Geophysical Union

  •  
     
     

    THE GEOLOGICAL SOCIETY OF JAPAN

  •  
     
     

    JAPAN ASSOCIATION OF MINERALOGICAL SCIENCES

  •  
     
     

    THE VOLCANOLOGICAL SOCIETY OF JAPAN

 

Research Areas

  • Disaster prevention engineering

  • Solid earth sciences

Research Interests

  • Volcanic ash

  • Magma

  • 火山噴火

Papers

  • Petrological Analyses of Phenocrysts in Volcanic Rock-1 -Basic Observation and Analytical Methods-

    Yuki SUZUKI

    Bulletin of the Volcanological Society of Japan    2022  [Refereed]

  • Conduit processes during the climactic phase of the Shinmoe-dake 2011 eruption (Japan): Insights into intermittent explosive activity and transition in eruption style of andesitic magma

    Yuki Suzuki, Fukashi Maeno, Masashi Nagai, Hitomi Shibutani, Syouhei Shimizu, Setsuya Nakada

    Journal of Volcanology and Geothermal Research   358   87 - 104  2018.06  [Refereed]

     View Summary

    © 2018 Elsevier B.V. The climactic phase of the Shinmoe-dake 2011 eruption was characterized by sub-Plinian events (January 26 p.m., 27 a.m., and 27 p.m.) and lava accumulation in the crater (late on January 27 to January 29), all of which were accompanied by Vulcanian events. The magma discharge rate for lava accumulation was close to that of the sub-Plinian events. We discuss evolution of syneruptive magma ascent through the climactic phase on the basis of decompression-induced crystallization of groundmass microlites, in order to reveal how the final eruption style was determined at the explosive–effusive transition. We examined pumice and lava-like pyroclasts from three sub-Plinian events, the January 28 Vulcanian event, and a lava block ballistically ejected during the February 1 Vulcanian event. The samples exhibit variable groundmass textures due to variable syneruptive ascent conditions, not due to pre-eruptive inhomogeneity of the andesitic magma and different degrees of syneruptive volatile exsolution preceding quenching. Eruptive units were first characterized according to bulk density, assuming that slower ascent resulted in higher density. A decrease in the magma ascent rate led to a gradual shift to an effusive eruption style. There was little variation in ascent rate among magmas erupted simultaneously during the first and second sub-Plinian events (bulk density 0.8–2.1 g/cm3), but differences increased in the third sub-Plinian and January 28 Vulcanian eruptions with minor appearance of slow magma (0.9–2.8 g/cm3). Only slow magma occupied the shallow conduit at the completion of lava accumulation (February 1 lava; 2.1 g/cm3). Among the first and second sub-Plinian units, the early stage of the second sub-Plinian event had the greatest variation in ascent rate, with extension to a slightly higher bulk density (1.0–2.1 g/cm3) than the other events (0.8–1.7 g/cm3). Ascent-rate variations in the early stage of the second sub-Plinian event, the third sub-Plinian event, and the January 28 Vulcanian event are all due to the preceding calm phase in the intermittent explosive activity. The moving magma column, which showed a vertical zonation in the degree of degassing, formed in the shallow conduit during the calm phase due to a decrease in the discharge rate, and this resulted in the co-ejection of magmas with variable degassing upon the start of explosive events. The crystal size distribution (CSD) of plagioclase microlites constrains the syneruptive branching (i.e., a point of divergence) in ascent rate and eruption style, which occurred after the start of microlite crystallization. The CSDs of the different samples show differences only in small crystal sizes; slope at these size fractions is smallest for low-density (<2.0 g/cm3) pyroclasts from all eruptive phases, medium for high-density pyroclasts and lava (>2.0 g/cm3) of the January 28 and February 1 events, and greatest for high-density pyroclasts (>2.0 g/cm3) of the third sub-Plinian event. We propose, based on the similarity in CSD, that the shallow magma-feeding system was common for the two craters active during the January 28 explosive–effusive hybrid activity, where the Vulcanian event and emplacement of lava of the later February 1 event occurred in different parts of the original crater. The samples have variable plagioclase microlite number densities (1.4 × 105–3.5 × 106 mm−3), based on variations in small crystal sizes among different CSDs. This variability resulted not only from the usual increasing trend in number density with increasing degree of undercooling, but also the decreasing trend associated with the strong undercooling during explosive eruptions.

    DOI

  • Growth process of the lava dome/flow complex at Sinabung Volcano during 2013–2016

    Setsuya Nakada, Akhmad Zaennudin, Mitsuhiro Yoshimoto, Fukashi Maeno, Yuki Suzuki, Natsumi Hokanishi, Hisashi Sasaki, Masato Iguchi, Takahiro Ohkura, Hendra Gunawan, Hetty Triastuty

    Journal of Volcanology and Geothermal Research( Published online)    2017.06  [Refereed]

  • Groundmass microlite texture of ash from Sinabung Volcano during 2014-2015 eruption

    Kubota Satoshi, Suzuki Yuki, Nakada Setsuya

    PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN   2017 ( 0 ) 223 - 223  2017  [Refereed]

    DOI CiNii

  • Report of the IAVCEI 2017 Scientific Assembly

    HASHIMOTO Takeshi, TANAKA Ryo, UESAWA Shimpei, YAMADA Taishi, HASEGAWA Takeshi, KOZONO Tomofumi, MANNEN Kazutaka, NAKAMICHI Haruhisa, SUMITA Mari, SUZUKI Yuki, TAJIMA Yasuhisa, TAKAGI Akimichi

    BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN   62 ( 4 ) 189 - 196  2017  [Refereed]

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  • Methods to Investigate Syneruptive Magma Processes Using Textures in Ejecta─ A Review of Progress in Last 10 Years─

    Yuki Suzuki

    Bulletin of the Volcanological Society of Japan   61 ( 2 ) 367 - 384  2016.06  [Refereed]

    DOI

  • B3-05 Continuous lava dome/flow eruption at Sinabung Volcano, North Sumatra, Indonesia

    Nakada S., Yoshimoto M., Maeno F., Suzuki Y., Hokanishi N., Iguchi M., Ohkura T., Zaennudin A., Hendrasto M.

    PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN   2015 ( 0 ) 81 - 81  2015  [Refereed]

    DOI CiNii

  • Report of Cities on Volcanoes 8 Conference in Yogyakarta, Indonesia

    NAKAMICHI Haruhisa, TAKARADA Shinji, TOSHIDA Kiyoshi, NAMIKI Atsuko, MAENO Fukashi, MATSUSHIMA Takeshi, MANNEN Kazutaka, YOSHIMOTO Mitsuhiro, YAMADA Taishi, IGUCHI Masato, AOKI Yosuke, ICHIHARA Mie, ITOH Hideyuki, UEDA Hideki, OHMINATO Takao, SATO Izumi, SUGIMOTO Shin'ichi, SUZUKI Yuki

    BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN   60 ( 1 ) 47 - 62  2015

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  • Constraining tephra dispersion and deposition from three subplinian explosions in 2011 at Shinmoedake volcano, Kyushu, Japan

    Fukashi Maeno, Masashi Nagai, Setsuya Nakada, Rose E. Burden, Samantha Engwell, Yuki Suzuki, Takayuki Kaneko

    BULLETIN OF VOLCANOLOGY   76 ( 6 )  2014.06  [Refereed]

     View Summary

    Constraining physical parameters of tephra dispersion and deposition from explosive volcanic eruptions is a significant challenge, because of both the complexity of the relationship between tephra distribution and distance from the vent and the difficulties associated with direct and comprehensive real-time observations. Three andesitic subplinian explosions in January 2011 at Shinmoedake volcano, Japan, are used as a case study to validate selected empirical and theoretical models using observations and field data. Tephra volumes are estimated using relationships between dispersal area and tephra thickness or mass/area. A new cubic B-spline interpolation method is also examined. Magma discharge rate is estimated using theoretical plume models incorporating the effect of wind. Results are consistent with observed plume heights (6.4-7.3 km above the vent) and eruption durations. Estimated tephra volumes were 15-34x10(6) m(3) for explosions on the afternoon of 26 January and morning of 27 January, and 5.0-7.6x10(6) m(3) for the afternoon of 27 January; magma discharge rates were in the range 1-2x10(6) kg/s for all three explosions. Clast dispersal models estimated plume height at 7.1 +/- 1 km above the vent for each explosion. The three subplinian explosions occurred with approximately 12-h reposes and had similar mass discharge rates and plume heights but decreasing erupted magma volumes and durations.

    DOI

  • Syneruptive deep magma transfer and shallow magma remobilization during the 2011 eruption of Shinmoe-dake, Japan-Constraints from melt inclusions and phase equilibria experiments

    Yuki Suzuki, Atsushi Yasuda, Natsumi Hokanishi, Takayuki Kaneko, Setsuya Nakada, Toshitsugu Fujii

    JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH   257   184 - 204  2013.05  [Refereed]

     View Summary

    The 2011 Shinmoe-dake eruption started with a phreatomagmatic eruption (Jan 19), followed by climax sub-Plinian events and subsequent explosions (Jan 26-28), lava accumulation in the crater (end of January), and vulcanian eruptions (February-April). We have studied a suite of ejecta to investigate the magmatic system beneath the volcano and remobilization processes in the silicic magma mush. Most of the ejecta, including brown and gray colored pumice clasts (Jan 26-28), ballistically ejected dense lava (Feb 1), and juvenile particles in ash from the phreatomagmatic and vulcanian events are magma mixing products (SiO2 = 57-58 wt.%; 960-980 degrees C). Mixing occurred between silicic andesite (SA) and basaltic andesite (BA) magmas at a fixed ratio (40%-30% SA and 60%-70% BA). The SA magma had SiO2 = 62-63 wt.% and a temperature of 870 degrees C, and contains 43 vol.% phenocrysts of pyroxene, plagioclase, and Fe-Ti oxide. The BA magma had SiO2 = 55 wt.% and a temperature of 1030 degrees C, and contains 9 vol.% phenocrysts of olivine and plagioclase. The SA magma partly erupted without mixing as white parts of pumices and juvenile particles.
    The two magmatic end-members crystallized at different depths, requiring the presence of two separate magma reservoirs; shallower SA reservoir and deeper BA reservoir. An experimental study reveals that the SA magma had been stored at a pressure of 125 MPa, corresponding to a depth of 5 km. The textures and forms of phenocrysts from the BA magma indicate rapid crystallization directly related to the 2011 eruptive activity. The wide range of H2O contents of olivine melt inclusions (5.5-1.6 wt.%) indicates that rapid crystallization was induced by decompression, with olivine crystallization first (&lt;= 250 MPa), followed by plagioclase addition. The limited occurrence of olivine melt inclusions trapped at depths of &lt;5 km is consistent with the proposed magma system model, because olivine crystallization ceased after magma mixing. Our petrological model is consistent with a geophysical model that explains whole crustal deformation as being due to a single source located 7-8 km northwest of the Shinmoe-dake summit. However, even the shallowest estimated source of this deformation (7.5-6.2 km) is deeper than the SA reservoir, which thus requires a contribution of deeper BA magmas to the observed deformation.
    Remobilization of mush-like SA magma occurred in two stages before the early sub-Plinian event. Firstly, precursor mixing with BA magma and associated heating occurred (925-871 degrees C; stage-1 of &gt;= 350 h), followed by final mixing with BA magma (stage-2). MgO profiles of magnetite phenocrysts define timescales of 0.7-15.2 h from this final mixing to eruption. The mixed and heated magmas, and stagnant mush that existed in the SA reservoir in the precursor stage, were finally erupted together. Magnetite phenocrysts in the Feb 18 ash reveal the occurrence of continuous erosion of the stagnant mush during the course of the 2011 eruptive activity. (C) 2013 Elsevier B.V. All rights reserved.

    DOI

  • The outline of the 2011 eruption at Shinmoe-dake (Kirishima), Japan

    Setsuya Nakada, Masashi Nagai, Takayuki Kaneko, Yuki Suzuki, Fukashi Maeno

    Earth, Planets and Space   65 ( 6 ) 475 - 488  2013  [Refereed]

     View Summary

    The climactic phase of the 2011 eruption at Shinmoe-dake was a mixture of subplinian and vulcanian eruptive events, successive lava accumulation (lava dome) within the crater, and repetition of vulcanian events after the dome growth. It was preceded by inflation and elevated seismicity for about one year and by phreatomagmatic explosions of one week before. Small pyroclastic flows and ash-cloud surges formed during the subplinian events, when the eruption column reached the highest level and the vent was widened. A lava dome, which was extruded close to the vent of subplinian events, grew by swelling upward and filling the crater. After the vent was covered by the lava, an intense vulcanian event occurred from the base of the dome and the swelled dome became deflated. After that, vulcanian events were repeated for three months. Simultaneous eruption styles in the crater (vulcanian events, continuous ash emission and dome growth) and some phreatomagmatic events in the vulcanian stage probably are due to a complex upper-conduit system developed in water-saturated country rock.

    DOI

  • Precursory activity and evolution of the 2011 eruption of Shinmoe-dake in Kirishima volcano-insights from ash samples

    Yuki Suzuki, Masashi Nagai, Fukashi Maeno, Atsushi Yasuda, Natsumi Hokanishi, Taketo Shimano, Mie Ichihara, Takayuki Kaneko, Setsuya Nakada

    EARTH PLANETS AND SPACE   65 ( 6 ) 591 - 607  2013  [Refereed]

     View Summary

    After a precursory phreatic stage (2008 to 2010), the 2011 Shinmoe-dake eruption entered a phreatomagmatic stage on January 19, a sub-Plinian and lava accumulation stage at the end of January, a vulcanian stage in February-April, and a second phreatomagmatic stage in June-August. Component ratio, bulk composition, and particle size of the samples helped us define the eruptive stages. The juvenile particles were first found in the January 19 sample as pumice (8 vol%) and were consistently present as scoria and pumice particles thereafter (generally similar to 50 vol%, decreasing in weaker events). The January 19 pumice has water-quench texture. After the lava accumulation, particles of that lava origin came to account for 30 similar to 70 vol% of the ash. The second phreatomagmatic stage is proposed because of fine ash and long eruption period. The SiO2 contents of bulk ash are lower in post-January 19, 2011 eruptions, reflecting lower average SiO2 contents in 2011 ejecta than in past ejecta. The free-crystal assemblages were two pyroxenes + plagioclase + Fe-Ti oxides until 2010; olivine joined the assemblage in 2011, when juvenile ash was erupted. This change is consistent with the absence or smaller sizes of olivine phenocrysts in past ejecta.

    DOI

  • P26 Evolution of conduit flow during the 2011 eruption of Shinmoe-dake, Japan : insights into cyclic sub-Plinian activity and shifting eruption style of andesite magma

    Suzuki Y., Maeno F., Nagai M., Nakada S., Ichihara M.

    PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN   2013 ( 0 ) 126 - 126  2013  [Refereed]

    DOI CiNii

  • B1-22 Syneruptive deep magma transfer and shallow magma remobilization in 2011 eruption of Shinmoe-dake, Japan : Constraints from melt inclusions and phase equilibria experiments

    Suzuki Y., Yasuda A., Hokanishi N., Kaneko T., Nakada S., Fujii T.

    PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN   2012 ( 0 ) 68 - 68  2012  [Refereed]

    DOI CiNii

  • A2-12 Petrological characteristics and time evolution of the 2011 eruptive products from Shinmoe-dake in Kirishima volcano

    Suzuki Y., Yasuda A., Hokanishi N., Kaneko T., Nakada S., Hirabayashi J.

    PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN   2011 ( 0 ) 34 - 34  2011  [Refereed]

    DOI CiNii

  • P05 Preparation processes and evolution of the 2011 eruption of Shinmoe-dake : insights from volcanic ash

    Suzuki Y., Nagai M., Maeno F., Yasuda A., Hokanishi N., Kaneko T., Nakada S.

    PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN   2011 ( 0 ) 117 - 117  2011  [Refereed]

    DOI CiNii

  • Effect of syneruptive decompression path on shifting intensity in basaltic sub-Plinian eruption Implication of microlites in Yufune-2 scoria from Fuji volcano, Japan

    Yuki Suzuki, Toshitsugu Fujii

    JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH   198 ( 1-2 ) 158 - 176  2010.12  [Refereed]

     View Summary

    To constrain the timing and conditions of syneruptive magma ascent that are responsible for shifting eruption intensity we have investigated a basaltic sub-Plinian eruption that produced Yufune-2 scoria in Fuji volcano 2200 years ago We deduced magmatic decompression conditions from groundmass microlite textures including decompression path (i e evolution in decompression rate) and approximate decompression rate in order to relate them to eruption intensity The microlites revealed decompression conditions after water saturation at 700-1100 m depth
    The temporal change in scoria size indicates that the magma discharge rate and resultant eruption intensity Increased from unit a to unit b and then declined toward ending units d and e The overall decompression rate in each eruptive unit has a positive correlation with eruption intensity The variation in decompression rate was enlarged in the final units where the maximum remained the same as the peak through the eruption (0 13-022 MPa/s for units b and c) while the minimum was 0 025 MPa/s The large variation here is due to 1) variation in flow velocity across conduit and 2) part of the erupted magma in unit d experienced remarkably slow decompression (0 002-0 003 MPa/s) resulting from decreased overpressure in the reservoir following the major eruption of unit b Furthermore crystal size distribution (CSD) of microlites implied that the earliest erupted magma (unit a) had once been decompressed slowly (0 005-0 012 MPa/s) having been arrested by material in the conduit-vent system which was followed by an increase in decompression rate due to removal of the material at the initiation of the eruption In addition the magma that had been ascending slowly before the unit-d eruption may record the increase in decompression rate This increased rate resulted from being pushed up by the successive magma at the start of that eruption
    Two factors had a major impact on eruption intensity First magma decompression rate determined the degree of gas phase separation from ascending magma Judging from CSD different decompression rates had been generated at least at the start of microlite crystallization The second factor is the conduit radius that in combination with magma ascent rate controlled the magma discharge rate Before the major eruption of unit b the conduit radius likely Increased as evidenced by xenoliths of basaltic lava and lithic fragments with the same petrography as the xenoliths in unit a. In unit e the conduit radius decreased through inward development of high-density magma from the conduit margin (c) 2010 Elsevier B V All rights reserved

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  • Course and Ejecta of the Eruption of Asama Volcano on 2 February 2009

    MAENO Fukashi, SUZUKI Yuki, NAKADA Setsuya, KOYAMA Etsuro, KANEKO Takayuki, FUJII Toshitsugu, MIYAMURA Jun'ichi, ONIZAWA Shin'ya, NAGAI Masashi

    BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN   55 ( 3 ) 147 - 154  2010  [Refereed]

     View Summary

    Asama volcano erupted in the midnight of 2 February 2009 with the ejection of ash and ballistics. The ash was dispersed toward the southeast, and observed in areas up to the southeast of the Kanto plain in the next morning. The ash fall deposits at the southeastern foot of the volcano were surveyed in order to determine a dispersal axis and detail isopleth contours. Isopleth contours of the ash fall deposit stretch out long from northwest to southeast, and they are denser in the western side of the dispersal axis than in the east. In the summit crater area, the ash is not recognized in the northern side. These indicate that the distribution of ash fall was strongly affected by a wind from the northwest. Based on the isopleth contour map, the total weight of ash fall is estimated to be 27,000-31,000ton, using a log area (m2)-log weight (g/m2) plot. The weight is approximately three fifth of the eruption on 1 September 2004 and the same order as ones on 13 November 2004 and 26 April 1982. Major components of the ash sampled at about 8km southeast from the source are non-altered and altered lava, individual crystals, and ceramisite, but minor glass particles (less than 1wt%) are also included in fine grains. The glass particles can be identified as juveniles and divided into two groups based on their shape and glass composition. One is 'dense-type' with rhyolitic composition which is the same as juveniles in the 2004 eruption, and the other is 'vesicular-type' with dacitic composition which is different from any juveniles in the recent eruptions including the 1783 Tenmei eruption. These chemical characteristics of juvenile particles indicate that two-types of magma have recently coexisted beneath Asama volcano and were erupted on 2 February 2009.

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  • P14 Juvenile ash of an small eruption at Mt. Asama on August 10, 2008

    Suzuki Y., Furukawa A., Nakada S., Fujii T., Watanabe A., Koyama E.

    PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN   2008 ( 0 ) 106 - 106  2008  [Refereed]

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  • Remobilization of highly crystalline felsic magma by injection of mafic magma: Constraints from the middle sixth century eruption at Haruna Volcano, Honshu, Japan

    Yuki Suzuki, Setsuya Nakada

    JOURNAL OF PETROLOGY   48 ( 8 ) 1543 - 1567  2007.08  [Refereed]

     View Summary

    The latest eruption of Haruna volcano at Futatsudake took place in the middle of the sixth century, starting with a Plinian fall, followed by pyroclastic flows, and ending with lava dome formation. Gray pumices found in the first Plinian phase (lower fall) and the dome lavas are the products of mixing between felsic (andesitic) magma having 50 vol.% phenocrysts and mafic magma. The mafic magma was aphyric in the initial phase, whereas it was relatively phyric during the final phase. The aphyric magma is chemically equivalent to the melt part of the phyric mafic magma and probably resulted from the separation of phenocrysts at their storage depth of similar to 15 km. The major part of the felsic magma erupted as white pumice, without mixing and heating prior to the eruption, after the mixed magma (gray pumice) and heated felsic magma (white pumice) of the lower fall deposit. Although the mafic magma was injected into the felsic magma reservoir (at similar to 7 km depth), part of the product (lower fall ejecta) preceded eruption of the felsic reservoir magma, as a consequence of upward dragging by the convecting reservoir of felsic magma. The mafic magma injection made the nearly rigid felsic magma erupt, letting low-viscosity mixed and heated magmas open the conduit and vent. Indeed the lower fall white pumices preserve a record of syneruptive slow ascent of magma to 2 km depth, probably associated with conduit formation.

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  • Experimental constraints on syneruptive magma ascent related to the phreatomagmatic phase of the 2000AD eruption of Usu volcano, Japan

    Yuki Suzuki, James E. Gardner, Jessica F. Larsen

    BULLETIN OF VOLCANOLOGY   69 ( 4 ) 423 - 444  2007.02  [Refereed]

     View Summary

    We experimentally studied the dacitic magma ejected during the first event in the Usu 2000 eruption to investigate the conditions of syneruptive magmatic ascent. Geophysical data revealed that the magma reached under West Nishiyama, the location of the event's craters, after rising beneath the summit. Prior study of bubble-size distributions of ejecta shows two stages (stage 1 and stage 2) with different magma ascent rates, as the magma accelerated beneath West Nishiyama with the start of the second stage. To simulate ascent of stage 1 from the main reservoir, which was located at a depth of 4-6 km (125 MPa) to 2 km (50 MPa) beneath West Nishiyama, decompression experiments were conducted isothermally at 900 degrees C following two paths. Single step decompression (SSD) samples were decompressed rapidly (0.67 MPa/s) to their final pressure and held for 12 to 144 hours. Multiple step decompression (MSD) samples were decompressed stepwise to their final pressure and quenched instantly. In MSD, the average decompression rates and total experimental durations varied between 0.01389 to 0.00015 MPa/s and 1.5 to 144 hours, respectively. Syneruptive crystallization was confined to stage 1, and the conditions of ascent were determined by documenting similarities in decompression-induced crystallization between ejecta and experiments. Core compositions, number densities, and shapes of experimental microlites indicate that ascent to 2 km depth occurred in less than 1.5 h. Volumes and number densities of experimental microlites from the SSD experiments that best replicate the decompression rate to 2 km indicate that the magma remained at 2 km for approximately 24 h before the eruption. Stagnation at a depth of 2 km corresponds with horizontal transport through a dike from beneath the summit to West Nishiyama, according to geodetic results. The total magma transport timescale including stage 2 is tens of hours and is shorter than the timescale of precursory seismicity (3.5 days), indicating that the erupted magma did not move out of the reservoir for the first 2 days. This is consistent with the temporal change in numbers of earthquakes, which reached a peak after 2 days.

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  • Syneruptive magma ascent revealed by crystallization processes : Recent progresses with decompression experiments

    SUZUKI Yuki

    Bulletin of the Volcanological Society of Japan   51 ( 6 ) 373 - 391  2006.12  [Refereed]

     View Summary

    This paper reviews the principles and the methods used to investigate the ascent process of water-saturated magmas based on crystal texture and composition, which are especially relevant to recent progress made in decompression experiments. The primary cause of syneruptive crystallization is an increase in the liquidus temperature and resultant undercooling due to a decrease in dissolved H_2O in the melt. Analyses of ejecta crystal texture provide time-resolvable information. Firstly, recent decompression experiments have improved knowledge regarding crystallization kinetics and have confir...

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  • Vesiculation and Magma Ascent Process in the Usu 2000 Eruption, Inferred from Texture and Size Distribution of Bubbles(<Special Section>The 2000 Eruption of Usu Volcano (3))

    SUZUKI Yuki, NAKADA Setsuya

    Bulletin of the Volcanological Society of Japan   47 ( 5 ) 675 - 688  2002.11  [Refereed]

     View Summary

    Study on products of phreatomagmatic eruption on 31 March 2000 at Usu volcano gives insight into timing of bubble nucleation and gas escape from system during magma ascent from the reservoir. The essential fragrnents (pumice and micropumice) vary in vesicularity which is negatively correlated to water content in the rhyolitic groundmass glass. This implies that variable vesicularity resulted from different degree of water exsolution from melt to bubbles, rather than different degree of gas escape. The difference in water exsolution probably reflects the different timing of quenching, where ...

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  • Timing of vesiculation and crystallizationduring magma ascent-Example of the phreatomagmatic phase in Usu 2000eruption-

    Suzuki Yuki, Nakada, Setsuya

    Bulletin of the Earthquake Research Institute, University of Tokyo   76 ( 2 ) 253 - 268  2001  [Refereed]

    CiNii

  • Petrogenesis of Felsic Magma in Higashi-Izu Monogenetic Volcano Group

    SUZUKI Yuki

    Bulletin of the Volcanological Society of Japan   45 ( 3 ) 149 - 171  2000.07  [Refereed]

     View Summary

    The activity of Higashi-Izu monogenetic volcano group produced basalt, andesite, dacite, and rhyolite, which can be classified into rock types by whole-rock composition and phenocryst assemblage. It has been widely accepted that felsic upper crust has an important role in forming compositionally diverse ejecta; andesites are formed through the assimilation of felsic crust by the basaltic magma and the felsic magmas through remelting of the felsic crust. To reinvestigate genesis of felsic magma, I examine the physicochemical conditions of both pre-eruption felsic magmas and the felsic crust....

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  • Petrology of ejecta from Futatsudake in Haruna Volcano

    Suzuki Yuki, Nakada Setsuya

    Annual Meeting of the Geological Society of Japan   1998 ( 0 ) 307 - 307  1998  [Refereed]

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Awards

  • 科学研究費補助金審査委員表彰

    2017.10  

    Winner: 鈴木 由希

  • 日本火山学会研究奨励賞

    2008.05  

    Winner: 鈴木由希

Research Projects

  • マッシュ状マグマの再流動化時間と噴火規模-斑晶の元素拡散記録からの制約-

    科学研究費補助金  基盤研究(C)

    Project Year :

    2019.04
    -
    2022.03
     

    鈴木 由希

  • 複数種斑晶の拡散現象を用いたマッシュ状珪長質マグマ噴火準備·誘発モデルの高精度化

    科学研究費補助金·基盤研究(C)

    Project Year :

    2013.04
    -
    2016.03
     

    鈴木由希

Specific Research

  • 成層火山の小規模カルデラ噴火の推移とマグマ供給系

    2019  

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    榛名火山で45kaに起きたカルデラ噴火が研究対象である。前年度までに、この噴火で生成した白川・里見火砕流堆積物の軽石には岩石学的な差異がないことを明らかにしていた(全岩SiO262-66wt.%;斑晶組み合わせは斜長石+斜方輝石+角閃石+カミングトン閃石+Fe-Ti&nbsp;酸化物+石英)。白川火砕流堆積物について榛名山南麓の荒神露頭の最上部ユニットを追加で分析した。軽石全岩SiO2量は62-63wt.%という前述の中では低い値に集中しており、今後その成因を明らかにする必要が生じた。白川・里見火砕流堆積物の両方の軽石から、代表的試料を選び出しモード分析も行った。斑晶量が45-60 vol.%の範囲にあり、噴火に関わった珪長質マグマがマッシュ状であることが確かめられた。

  • 斑晶中の元素拡散から探るマッシュ状マグマ再流動化時間・複数噴火のマッシュの関係

    2018  

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    榛名火山新期活動(45ka〜)のマグマを研究し、次を明らかにした。1)どの噴火でも結晶に富むマッシュ状珪長質マグマが関与しており、それに高温マグマが注入して噴火に至ったこと、2)マッシュはどの噴火でもデイサイト質である。二ツ岳の2噴火(渋川・伊香保;5〜6世紀)のマグマは互いに良く似ており、同一のマグマ溜りに由来した可能性が高いこと、3)45 ka〜10kaに活動した高温マグマは二ツ岳伊香保噴火(Suzuki and Nakada, 2007)の高温マグマと類似した組成であること。以上に基づき、マッシュ状マグマの噴火準備・誘発過程を探る科研費を申請したところ採択された(2019〜2021年度)。&nbsp; &nbsp;&nbsp;

  • 珪長質マグマ噴火の誘発過程の岩石学的研究

    2015  

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     珪長質マグマの噴火誘発過程に関する岩石学的研究を実施した。対象の一つは、新期榛名火山の活動で形成された山頂溶岩ドーム群である。これらは、マッシュ状珪長質マグマが、高温マグマと混合したか、高温マグマにより加熱されることで形成されたもので、榛名山最新の二ツ岳ドームと同様の噴火誘発過程が働いていることが分かった。もう一つの対象は、鬼界7.3kaのカルデラ噴火に先立ち噴出した長浜溶岩である。カルデラ形成期に珪長質マグマと高温マグマの混合マグマが噴出していることから、長浜溶岩に高温マグマの先駆的注入の記録があることを期待した。しかし珪長質マグマそのものが噴出したものであることが判明した。

  • 安山岩質マグマの噴火様式決定過程-新燃岳2011年噴火の例-

    2014  

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    新燃岳2011年噴火の最盛期を対象に火道でのマグマ上昇の進化と噴火様式の関連を研究した。準プリニー式噴火の軽石並びに火口蓄積溶岩の石基結晶を解析した。石基結晶度はマグマの上昇速度を反映するが軽石と比べ溶岩で高く、石基結晶度が高い程“みかけ密度”も高い。すなわち火道での上昇速度が遅いほど脱ガスも進み、噴火が非爆発的になる機構が働いていた。準プリニー式噴火は約12時間の噴火“静穏期・休止期”を挟んで3度起きた。 活動再開直後の堆積物には“みかけ密度”“石基結晶度”が高い粒子が含まれる。これらは噴火の静穏期・休止期に低速で上昇し脱ガスも進んだマグマに由来し、直後のイベントで集中的に放出された。

 

Syllabus

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Teaching Experience

  • 自然科学総合実験

    東北大学  

  • 地球科学

    東北大学  

  • 顕微鏡実習

    東北大学  

  • 夏期地質調査実習

    東北大学  

 

Committee Memberships

  • 2021.04
    -
    Now

    文部科学省・科学技術・学術審議会 測地学分科会(第11期)  火山研究推進委員会 専門委員

  • 2018.04
    -
    Now

    次世代火山研究者育成プログラム  プログラム担当者

  • 2020.05
    -
    2021.02

    文部科学省・科学技術・学術審議会 測地学分科会(第10期)  火山研究推進委員会 専門委員

  • 2018.04
    -
    2020.03

    東京大学地震研究所  共同利用委員会委員

  • 2016.07
    -
    2018.06

    日本火山学会  庶務委員

  • 2014.07
    -
    2018.06

    日本火山学会  編集委員

  • 2016.06
    -
    2018.05

    日本地球惑星科学連合  ダイバーシティ推進委員会委員(日本火山学会選出)

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