研究者業績

本多 嘉明

ホンダ ヨシアキ  (Yoshiaki Honda)

基本情報

所属
千葉大学 環境リモートセンシング研究センターリモートセンシング基盤研究領域 准教授
学位
工学博士(1991年3月 東京大学大学院工学系研究科)

J-GLOBAL ID
200901001950469000
researchmap会員ID
1000161948

論文

 254
  • Toshiyuki Kobayashi, Hideki Kobayashi, Wei Yang, Hiroshi Murakami, Yoshiaki Honda, Kenlo Nishida Nasahara
    ISPRS Journal of Photogrammetry and Remote Sensing 202 479-498 2023年8月  査読有り
  • Takayuki Kaneko, Fukashi Maeno, Mie Ichihara, Atsushi Yasuda, Takao Ohminato, Kenji Nogami, Setsuya Nakada, Yoshiaki Honda, Hiroshi Murakami
    Earth, Planets and Space 74(1) 2022年12月  査読有り
    In December 2019, a new activity started at Nishinoshima volcano in the southern part of the Izu–Ogasawara arc, Japan. This is now referred to as Episode 4 of a series of activities that began in 2013. We analyzed the eruption sequence, including erupted volume and effusion rate, based on combined observations of thermal anomalies by Himawari-8 and topographic changes by ALOS-2. The total eruption volume during Episode 4 was ~ 132 × 106 m3, and the average effusion rate over the entire period was 0.51 × 106 m3 day−1 (5.9 m3 s−1), which was two to three times higher than that of Episode 1. Episode 4 had three stages. In Stage 1, effusive activity was dominant, and most of the lava erupted from a northeast vent at the foot of the pyroclastic cone to cover the northern half of the island. The average effusion rate was estimated to be 0.46 × 106 m3 day−1 (5.3 m3 s−1). In Stage 2, an intensive lava fountain with a high discharge rate developed, and it increased the size of the pyroclastic cone rapidly. The effusion rate temporarily reached 2.6 × 106 m3 day−1 (30 m3 s−1). Pyroclastic rocks accounted for 45–88% of the total erupted volume in this stage. Lava flows with rafted cone material were generated, and those possibly caused by intensive spatter falls on the slope were also formed. These lavas flowed down the southern half of the island. In Stage 3, continuous phreatomagmatic eruptions released ash and spread it over a wide area. The high effusion rate and the drastic change in the activity style in Episode 4 can be explained by deep volatile-rich magma being supplied to a shallower magma chamber prior to Episode 4. When the volatile-rich magma reached a shallow part of the conduit in Stage 2, fragmentation occurred due to rapid volume expansion to eject large amounts of magma and form the intensive lava fountain. Observations by satellite-borne ultraviolet–visible image sensors detected a rapid increase in SO2 emissions in response to the intensive lava-fountain activity. The less-differentiated nature of the ash fragments collected during Stage 2 may reflect the composition of the volatile-rich magma. Large-scale discolored-seawater areas appeared during the late period of Stage 1, which may have been caused by ascent of the volatile-rich magma. Graphical Abstract: [Figure not available: see fulltext.].
  • Takao Koyama, Takayuki Kaneko, Takao Ohminato, Atsushi Watanabe, Yoshiaki Honda, Takahiro Akiyama, Shinichi Tanaka, Marceau Gresse, Makoto Uyeshima, Yuichi Morita
    Journal of Disaster Research 17(5) 644-653 2022年8月1日  査読有り
    Miyakejima volcano experienced its latest eruption in 2000 with the summit subsidence, and the next event is expected in the near future. An aeromagnetic survey in Miyakejima was conducted in March 2021 in order to investigate the current state of its magnetization structure to identify the potential for another eruption and, thus, mitigate volcanic disaster. The survey flight was conducted using an uncrewed aerial vehicle (UAV), a multirotor drone, to deploy a scalar magnetometer. After processing geomagnetic field data from this survey, in combination with data from previous surveys conducted by using another UAV, an uncrewed helicopter, the average magnetization intensity was determined to be 12.4 A/m. Further, the surrounding area of the crater was relatively highly magnetized; however, the crater rim had a low magnetization intensity. Temporal variation was detected between 2014 and 2021 and dominated the central part of the observation area. Decreased magnetization intensity was identified beneath the caldera, which may become recently demagnetized due to heat supply traveling through fractures in the impermeable layer from the deep heat reservoir.
  • Takao Koyama, Takayuki Kaneko, Takao Ohminato, Atsushi Yasuda, Tsutomu Ogawa, Atsushi Watanabe, Shikou Sakashita, Minoru Takeo, Takatoshi Yanagisawa, Yoshiaki Honda, Koji Kajiwara
    Journal of Volcanology and Geothermal Research 425 2022年5月  査読有り
    We conducted a high-resolution aeromagnetic survey using an autonomously driven uncrewed helicopter that flew as low as several tens of meters above the ground along precise flight tracks with 1 m accuracy. The geomagnetic total intensity was measured by a total intensity magnetometer suspended beneath the helicopter at a ~ 50 m or less flight spacing over the entire caldera of Mt. Mihara, located on Izu-Oshima Island, Japan. From the observed geomagnetic data, we estimated high-resolution subsurface magnetization intensity. A high average magnetization intensity of 13.5 A/m was obtained for the entire caldera. The distribution of the magnetization intensity was not only consistent with the results of conventional airborne surveys, but it also had a high spatial resolution of less than 100 m. Highly magnetized areas were observed along the NW–SE lines that intersected the summit pit crater, Crater A, which is consistent with the principal stress direction of Izu-Oshima Island. These highly magnetized areas might be solidified magma that did not reach the surface during past eruptions. A large and deep-rooted weakly magnetized area was found just outside of the NE side of the central cone, which corresponds to the location of Fissure B, and the conduit must have been demagnetized at the previous event. Other weakly magnetized areas were also observed at the N, E, and SW sides around the pit crater. These regions correspond to the location of fumaroles in the crater. The high-resolution subsurface magnetization imaged by the autonomous uncrewed helicopter will be helpful for the mitigation of future eruption damage by enabling the assessment of potential fissure eruption areas.
  • 小山 崇夫, 金子 隆之, 大湊 隆雄, 渡邉 篤志, 柳澤 孝寿, 本多 嘉明
    物理探査 74 115-122 2021年12月  査読有り
    無人飛翔体は被災するおそれのある危険地域へ人が入域することなく各種測定を実施することを可能とするため,今世紀に入ってから特に着目され,現在までに多様な火山観測項目に利用されている。その中で自律型無人ヘリコプターは,高い位置精度で事前にプログラミングした航路に沿ってフライトすることが可能になるため,たとえば対地高度や測線間隔を一定に保つなど理想的な測線を組むことが可能になることに加えて,時間間隔をおいて同一の測線に沿って繰り返し観測を実施することで同一地点での観測量の時間変化を捉えることが可能となる。そのため,火山体での空中磁気測量を自律型無人ヘリコプターを用いて実施することにより,複雑な地形上でも均質な空間解像度の磁場測定を可能にし,また,複数回繰り返し行うことで噴火準備過程などの火山活動に伴う磁場の長期的な時間変化を検出することができる。伊豆大島三原山では対地高度および測線間隔を平均50 mとした稠密な空中磁気測量を実施し,過去に噴出せず地下で固化したと考えられる高磁化の領域が中央火口丘周辺に確認された。霧島新燃岳では2011年噴火活動以降繰り返し空中磁気測量を実施することにより,火口内に滞留した溶岩が冷却帯磁により時間を追って磁化を獲得していく様子を明瞭に検出することができた。ここ数年は電動式マルチコプターの開発およびその利用がめざましく,今後も無人飛翔体による火山観測のさらなる発展が期待される。

MISC

 171

書籍等出版物

 2

講演・口頭発表等

 17

担当経験のある科目(授業)

 11

共同研究・競争的資金等の研究課題

 19

産業財産権

 2

社会貢献活動

 1

メディア報道

 3
  • 静岡新聞 静岡新聞 地域(東),21面 2017年10月18日 新聞・雑誌
    1) 御殿場市は5日、民間団体と協力してドローンなどの無人航空機(UAV)を活用した測量技術の研究開発に向けた取り組みを、同市水土野の富士フェニックス短大跡地を拠点に進めると発表した。同所で12日に試験飛行を実施し、正式な協定を結ぶ。市によると、協定が実現すれば、全国初のUAVによる測量技術の研究開発場所となるという。民間団体は大学や航空測量会社からなる「地上測量のためのUAV運用研究会」。試験飛行ではカメラやセンサーを付けたドローンを飛ばして地形を調査し、データを基にマップを作成する。同短大跡地の面積は約3ヘクタール。標高差は30メートルほどで、校舎や森林、水路などがある。適度な広さと起伏のため、測量テストに向いた地形という。団体側から土地所有者である市に申し入れがあり、周辺地権者の了承を取り付けて実現した。市は2016年12月、ドローンによる災害時の情報収集や市の魅力発信の強化などに向け、NPO法人ふじのくにSKYイノベーション(浜松市)と協定を結ぶなど、UAVの利活用に力を入れている。御殿場市の担当者は「国内初のドローンを活用した空間情報計測技術の調査場所となれば、市のPRになる。航空産業をはじめとする関連企業の誘致など地域活性化にもつなげたい」と話した。
  • NHK NHKニュース「おはよう日本」 2002年12月14日 テレビ・ラジオ番組
    平成14年12月14日の地球観測衛星の打ち上げに合わせて、衛星を利用した最先端の地球温暖化研究を紹介する。