著者

長谷川 健 菊池 文太 柴田 翔平 井村 匠 伴 雅雄 常松 佳恵 山本 裕二 大場 司 鈴木 和馬 戸丸 淳晴 楠 稚枝 岡田 誠

出版者

特定非営利活動法人 日本火山学会

雑誌

火山 (ISSN:04534360)

巻号頁・発行日

vol.68, no.3, pp.189-196, 2023-09-30 (Released:2023-11-02)

参考文献数

22

---

Volcanic bomb is one of the most common eruption products around their source craters. Although paleomagnetic studies on volcanic bombs have a potential to provide high-resolution chronology of volcanic activity, particularly when compared with the known geomagnetic secular variation records, there are only a few such studies. In this contribution, we made an attempt to determine paleomagnetic directions from large (>1 m in diameter) volcanic bombs around “Tsubakuroswa craters”, located in Azuma volcano, for evaluating the potential use of volcanic bombs for paleomagnetic dating. Six oriented mini-cores were drilled from the central part of each large volcanic bomb, five in total, located on a gentle slope a few hundred meters south from the craters. All of the mini-cores were subjected to thermal demagnetization analysis, giving a well-determined characteristic remanent magnetization (ChRM) direction for each bomb as follows: site mean declination (Dm) of 350.6‒358.0º and inclination (Im) of 48.9‒50.8º with a 95 percent confidence limit (α95) smaller than 2.4º. The ChRM directions were consistent among the bombs, supporting the availability of volcanic bombs for further paleomagnetic dating research. Referring the geomagnetic secular variation record in this area, an all-site mean ChRM direction from the five bombs (Dec=355.5º, Inc=50.1º, α95=1.9º) most likely accounts for the derivation of the volcanic bombs by the Meiji Era (1893 CE) eruption. Historic pictures and descriptions are consistent with and support this interpretation. Previous reports suggested that the Meiji Era eruption did not eject magmatic materials and that the last magmatic eruption of this volcano was probably in 1331 CE. However, our results suggest that magmatic eruptions might have occurred here only ca. 130 years ago and may be largely affecting the current activity of this crater area. Our study suggests that volcanic bombs are potentially useful materials for paleomagnetic studies such as dating and establishing geomagnetic secular variation records.

著者

蔭山 雅洋 山本 雄平 田中 成典 柴田 翔平 鳴尾 丈司

出版者

日本知能情報ファジィ学会

雑誌

日本知能情報ファジィ学会 ファジィ システム シンポジウム 講演論文集 第34回ファジィシステムシンポジウム

巻号頁・発行日

pp.49-54, 2018 (Released:2019-01-09)

---

平成25年に文部科学省が報告した運動部活動での指導のガイドラインでは, 指導者が効果的な指導を行うには, 自身の経験に頼るだけでなく, スポーツ医・科学の研究の成果を積極的に習得し, 活用することが重要であるとされている. 近年では, センサ技術やIT技術の発展により, 計測装置の小型化が進み, バッティング直後に, スイングの結果を即時にフィードバックできる計測装置が開発されている. この計測装置では, 取得された計測データから打者のバットスイングの特徴を計測することが可能となる. しかしながら, アマチュア野球選手の指導現場では, 未だに, 科学的なデータに基づいた指導方法は, 確立されていない. その原因として, これまで我が国の野球において, 合理的な指導と非合理的な指導が混在していることに加えて, 算出された数値に対する解釈が難しいことが考えられる. そこで, 本研究では, これまで得られたデータに基づき作成した評価シートの提示が高校野球選手の打撃に関する理解および意欲に及ぼす効果を検討し, スイング計測装置を用いた打撃指導に役立てることを目的とする.

著者

柴田 翔平 長谷川 健

出版者

特定非営利活動法人 日本火山学会

雑誌

火山 (ISSN:04534360)

巻号頁・発行日

vol.67, no.2, pp.149-169, 2022-06-30 (Released:2022-07-28)

参考文献数

48

---

We studied the 40 ka Kp I eruption deposits of Kutcharo volcano to unravel its eruption sequence and generation mechanisms. Previous studies have suggested that Kp I is the youngest caldera-forming eruption in this volcano and is characterized by large-scale phreatomagmatic activity. We divided Kp I eruption deposits into 7 units (Units 1~7, in ascending order). Units 1~6 consist of alternating thin pumice and thick fine ash layers. Units 1, 3, and 5 are pumice falls (totaling 1.6 km3), while Units 2, 4, and 6 are ash falls (totaling 52.2 km3) with abundant accretionary lapilli. Stratigraphically higher ash fall units are larger in volume, finer in grain size, and more widely distributed (e.g., Units 2, 4, and 6 are 0.2 km3, 13 km3, 39 km3 respectively). Unit 7 is a climactic ignimbrite (76 km3) that subdivides into lower (Unit 7-L), and upper (Unit 7-U) parts based on the pumice size and the existence of a lithic concentration zone (LCZ).Considering its wide dispersion, high fragmentation, and existence of abundant accretionary lapilli, Unit 6 can be considered to have been deposited by a “phreatoplinian style” eruption. Even though the ejected magma volume increased during the eruption of Unit 1 to 6, interaction between ascending magma and ground water caused maximum explosivity during the eruption that deposited Unit 6. Highly fragmentated magmas might have promoted vaporization and mixing with surface (lake) water to form the buoyant eruption column of Unit 6 eruption phase. Unit 7 is the most voluminous and the richest in lithic fragments at the LCZ, suggesting caldera collapse that generated a climactic pyroclastic flow.In addition to glass shards of bubble wall and pumiceous types, Kp I eruption deposits also commonly contain flake-, and blocky-shaped glass shards produced by phreatomagmatic (quenching) fragmentation. For both types of glass shards to have been generated, part of the ascending magma would have interacted with ground water before and/or during the magmatic fragmentation (vesiculation) that generally occurs below a depth of approximately 1,000 m in felsic H2O-saturated magma systems. In conclusion, a large and deep (~1,000 m) aquifer in the former caldera basin was sustainably supplied with ground water through the conduit system. Generation of the phreatoplinian eruption seems to have been controlled by a plumbing where conduits penetrated the huge aquifer of a pre-existing caldera structure that preserved/hosted a large amount of external water.

著者

長谷川 健 柴田 翔平 小林 哲夫 望月 伸竜 中川 光弘 岸本 博志

出版者

特定非営利活動法人 日本火山学会

雑誌

火山 (ISSN:04534360)

巻号頁・発行日

vol.66, no.3, pp.187-210, 2021-09-30 (Released:2021-10-29)

参考文献数

57

---

Based on detailed fieldwork, petrological and paleomagnetic investigations, we present a revised stratigraphy of deposits from the 7.6 ka eruption at Mashu volcano and the formation process of its summit caldera, eastern Hokkaido, Japan. As previously described, the eruption products consist of an initial phreatomagmatic unit (Ma-j) and the overlying three pumice-fall layers (Ma-i, -h, and -g), which are in turn overlain by pyroclastic-flow deposits (Ma-f). In the present study, we divide Ma-f into 4 subunits: Ma-f1/2, Ma-fAc, Ma-f3a and Ma-f3b in descending order. Ma-f3b is a valley-ponding, pumice-flow deposit with limited distribution. Ma-f3a comprises clast-supported facies (fines-depleted ignimbrite: FDI) and matrix-supported (normal ignimbrite) facies, the two changing across topography. The FDI is characterized by a gray, fines-depleted, lithic-breccia-rich layer with materials incorporated from the substrate. Impact sag structures from large (>50 cm) dacite ballistic blocks were recognized at the base of the Ma-f3a within 10 km from the source. Ma-fAc is a minor eruption unit consisting of accretionary lapilli. Ma-f1/2 is a most voluminous (8.8 km3), widely distributed and weakly stratified ignimbrite. Both Ma-f3a and Ma-f1/2 can be classified as “low aspect ratio ignimbrite (LARI)”. Dacite lithic fragments are ubiquitously observed throughout the sequence and are not considered to be juvenile; they have distinctly different chemical compositions from the pumice fragments in the early pumice-fall (Ma-g~Ma-i) and pyroclastic-flow (Ma-f3b) deposits, but those of pumice clasts in the late pyroclastic-flow units (Ma-f3a and Ma-f2) lie between the two on a FeO*/MgO vs. SiO2 diagram. The 7.6 ka caldera-forming eruption of the Mashu volcano was initiated by Plinian fall (Ma-j~-g), and then, a small-volume high aspect ratio ignimbrite (Ma-f3b) was deposited by a valley-confined pyroclastic flow that was generated by partial column collapse. After that, a violent pyroclastic flow was generated probably during a strong explosion of a dacite lava edifice on the summit of Mashu volcano. This flow emplaced Ma-f3a. The caldera collapse that followed the explosion generated a climactic pyroclastic flow that emplaced Ma-f1/2. Ma-f3a flow was extremely fast. Ma-f1/2 flow was related to sustained flow due to low settling velocity and high discharge volume. These are supported by field observations and numerical simulation that shows the ability of the flow to surmount high topographic obstacles and spread widely. The 7.6 ka caldera-forming process of Mashu volcano was driven not only by subsidence of roof block but also by violent explosions.

著者

柴田 翔平 鳴尾 丈司 加瀬 悠人 稲毛 正也 山本 道治 森 正樹 浦川 一雄 廣瀬 圭 神事 努

出版者

一般社団法人 日本機械学会

雑誌

シンポジウム: スポーツ・アンド・ヒューマン・ダイナミクス講演論文集 2018 (ISSN:24329509)

巻号頁・発行日

pp.A-18, 2018 (Released:2019-05-25)

---

The purpose of this study is to examine the accuracy of the system analyzing pitching data using baseball-type sensor (MAQ) and to measure kinematic parameter (ball velocity, spin rate, and spin axis) of baseball pitches by various pitchers. The accuracy of the developed system using a 3D motion analysis system and the high-speed cameras were examined. The spin axis of pitched ball was calculated from data of 12-axis sensor using the sensor fusion by extended Kalman Filter. The ball velocity and spin rate calculated by MAQ and the 3D motion analysis system showed similar values (ball velocity: r = 0.95 spin rate: r = 0.90). In several data, it was indicated that the spin axis calculated by MAQ, the 3D motion analysis system, and the high-speed camera showed similar values. In addition, there was a correlation between ball velocity and spin rate over the velocity range from 6.7 m/s to 41.0 m/s (n=188). From these results, the developed system can be used to evaluate baseball pitching skill with high accuracy.

著者

柴田 翔平 長谷川 健

雑誌

日本地球惑星科学連合2019年大会

巻号頁・発行日

2019-03-14

---

摩周火山は,北海道東部に位置し,山頂部に径7.5 km×5.5 kmのカルデラを有する.このカルデラは約7,600年前の大規模噴火(噴出量約20 km3)によって形成された(岸本ほか,2009,山元ほか,2010).従来の研究によるカルデラ形成噴出物の層序は,降下火砕堆積物(Ma-j~Ma-g)とそれを覆う火砕流堆積物(Ma-f)からなる(Katsui et al.1975).摩周カルデラ形成噴火の推移は,岸本ほか(2009)によって,マグマ水蒸気噴火(Ma-j)からはじまり,プリニー式噴火に移行,3層の降下軽石(Ma-i~Ma-g)を堆積させた後,噴煙柱崩壊による火砕流(Ma-f)が流下,摩周カルデラが形成されたと考えられている.一方,長谷川ほか(2017)は,Ma-fを層相の違いから7層(上位からMa-f1~Ma-f7)に細分し,摩周カルデラ形成噴火は従来の噴火推移よりも複雑であった可能性を指摘した.そこで,著者らは地質調査,カルデラ形成噴出物の粒度分析および構成物分析を行い摩周カルデラ形成噴火の推移を再検討した.粒度分析は-5Φ~4Φまでの範囲を1Φ間隔で行い,構成物分析は2~32 mmの粒子を肉眼観察で分類し,重量%を求めた.Ma-f6,Ma-f7は層相の類似する火砕物密度流堆積物(以下,堆積物を省略)で灰色軽石,縞状軽石に富み(それぞれ40~60wt%,5~21wt%),中央粒径(以下,MdΦ)は-1.00Φ~0.89Φ である.Ma-f5(降下火砕物)およびMa-f4(火砕物密度流)は火山豆石を多く含み(それぞれ89wt%,82wt%),軽石,石質岩片には例外なくシルト質火山灰が付着し,マグマ水蒸気噴火堆積物の特徴を有する.Ma-f4のMdΦは,-0.55Φ~3.22Φ であり,下位のMa-f6,Ma-f7よりも細粒な火砕物密度流である.Ma-f3は石質岩片を大量に含む(90wt%以上)礫支持の火砕物密度流で,デイサイト質岩片のほか,深成岩片,変質岩片も含み,しばしば下位層を著しく削り込む.MdΦは,-3.47Φ~-1.37Φ で,極細粒砂~シルト粒子を欠く.Ma-f2はしばしば斜交葉理をともなう火砕物密度流で,細礫サイズの石質岩片を多く含み(70wt%),軽石も含まれる(30wt%).MdΦは,-1.84Φ~1.16Φである.Ma-f1は褐色の火山灰層で,軽石および石質岩片を含み(それぞれ52wt%,48wt%),Ma-f2との層境界は不明瞭で漸移的に色調・粒径が変化する.MdΦは,-1.22Φ~1.80Φである.Ma-f3の上位には例外なくMa-f2,Ma-f1が堆積し,これらは分布域の広さからMa-fの体積の大部分を占めることが分かる.Ma-f下位の降下火砕物の構成物に目を向けると,Ma-i~Ma-gにかけて優勢な本質物質が白色軽石から,縞状軽石,灰色軽石へと変化する.Ma-f1~Ma-f7は,粒度組成および構成物組成からMa-f7~6,Ma-f5~4,Ma-f3~1にグループ分けすることができ,それぞれの境界で噴火様式が変化したと考えられる.Ma-f7~6は灰色軽石と縞状軽石が優勢で,これは下位のMa-i~Ma-gにかけて見られる本質物質の量比変化と連続的であることや石質岩片の種類も一致することから,Ma-i~Ma-f6までは一連の噴出物であると考えられる.噴出率の低下により噴煙柱が崩壊し,Ma-f7,6が流下したと考えられるが,その後,火道への外来水の相対的な流入量が増加し,噴火様式がマグマ水蒸気噴火に変化してMa-f5~4を発生したと考えられる.つづくMa-f3~1では石質岩片量が急増することと, Ma-fの大部分を占めることからカルデラ陥没開始が示唆される。Ma-f3の上位にはMa-f2,Ma-f1が例外なく堆積しており,これらに含まれる構成物は石質岩片の量比が変化するものの,その種類は変化せず,上位にかけてMdΦが細粒になることから,Ma-f3~Ma-f1は高速の火砕物密度流の流動単位,Layer 1~Layer 3(Wilson,1985)に対応すると考えられる.従来の噴火推移と合わせると,摩周カルデラ形成噴火はマグマ水蒸気噴火(Ma-j)にはじまり,プリニー式噴火に移行,降下軽石(Ma-i~Ma-g)を堆積させ,噴煙柱崩壊による火砕物密度流(Ma-f7~Ma-f6)を流下させた.その後,マグマ水蒸気噴火に移行(Ma-f5~Ma-f4),カルデラ陥没にともなう岩塊の放出と火砕物密度流が流下し(Ma-f3~Ma-f1),摩周カルデラが形成されたと考えられる.

著者

山本 啓介 城戸口 和希 鈴木 大河 小荒井 衛 今泉 利架 杉野 伊吹 遠藤 史隆 大友 眞太郎 小関 敏史 柴田 翔平 菅原 慎吾 渡部 将太

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 (ISSN:13483935)

巻号頁・発行日

vol.2017, 2017