Atsushi Watanabe

Tohoku University

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Takao Ohminato

The University of Tokyo

Takayuki Kaneko

The University of Tokyo

Takao Koyama

Association for the Development of Earthquake Prediction

Takeshi Matsushima

Kyushu University

Faisal Amri

Tokyo Institute of Technology

Kazuo Nadaoka

Tokyo Institute of Technology

Aditiya R. Kartadikaria

Bandung Institute of Technology

Hiroki Miyamachi

Kagoshima University

Takashi Nakamura

Tohoku University

Yoshiyuki Tanaka

The University of Tokyo

Cooperative Institutions

The University of Tokyo

Earthquake Engineering Research Institute

Association for the Development of Earthquake Prediction

Kyoto University

Kyushu University

Tohoku University

National Research Institute for Earth Science and Disaster Resilience

Hokkaido University

Geological Survey of Japan

National Institute of Advanced Industrial Science and Technology

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Aeromagnetic survey in volcanoes by using autonomous-driven unmanned helicopter

BUTSURI-TANSA(Geophysical Exploration) (2021)

Takao Koyama Takayuki Kaneko Takao Ohminato Atsushi Watanabe Takatoshi Yanagisawa

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。

Aeromagnetic survey

10.3124/segj.74.115

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Citations (1)

Supplementary material to "Seasonal to interannual variabilities of sea–air CO₂ exchange across Tropical Maritime Continent indicated by eddy–permitting coupled OGCM experiment"

Faisal Amri Takashi Nakamura Atsushi Watanabe Aditiya R. Kartadikaria Kazuo Nadaoka

S1: Formulation of low-trophic ecosystem modelModel employed in this study is primarily based on food web dynamic module in Nakamura et al. ( 2018) which uses governing equation from Kawamiya et al. (1995) and Kishi et al. (2001).The model simulates material transformation in oceanic low-trophic ecosystem level comprised of organic matter production by phytoplankton and zooplankton, mainly in

Seasonality

10.5194/egusphere-2022-1067-supplement

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Imaging S-wave scatterer distribution in southeast part of the focal area of the 2005 West Off Fukuoka Prefecture Earthquake (MJMA 7.0) by dense seismic array

Earth Planets and Space (2006)

Satoshi Matsumoto Atsushi Watanabe Takeshi Matsushima Hiroki Miyamachi S. Hirano

Abstract Spatial distribution of S -wave scatterers in the SE part of the focal area of the 2005 West Off Fukuoka Prefecture Earthquake ( M = 7.0) has been estimated using dense seismic array data. Waveforms of 22 natural earthquakes were analyzed in a frequency range of 16–24 Hz. It is difficult to estimate the inhomogeneous structure in this wavelength range with ordinary travel time tomography despite the importance of this parameter for understanding the earthquake-generating process. After filtering and gain recovery in the coda part, observed waveforms were semblance-enhanced slant-stacked into various directions from the array. This was followed by diffraction curve summation in order to image the scatterer distribution. The spatial distribution of scatterers thus imaged revealed that higher strengths were distributed at the SE-extension of the fault plane of the event, which corresponds to a region where the rupture process of the main shock stopped

Coda

Seismic array

10.1186/bf03352673

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Citations (7)

Geomagnetic total intensity change before and after the eruptions at Shinmoedake volcano in 2018 detected by aeromagnetic surveys

Japan Geoscience Union (2019)

Takao Koyama Takayuki Kaneko Takao Ohminato Atsushi Watanabe Fukashi Maeno

Intensity

Source

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Magnetization Structure and its Temporal Change of Miyakejima Volcano, Japan, Revealed by Uncrewed Aerial Vehicle Aeromagnetic Survey

Journal of Disaster Research (2022)

Takao Koyama Takayuki Kaneko Takao Ohminato Atsushi Watanabe Yoshiaki Honda

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.

Aeromagnetic survey

Magnetic survey

Caldera

Flood basalt

10.20965/jdr.2022.p0644

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Comment on egusphere-2022-1067

Faisal Amri Takashi Nakamura Atsushi Watanabe Aditiya R. Kartadikaria Kazuo Nadaoka

The lack of long–term observational data has limited research on sea–air CO2 exchange variabilities in the Tropical Maritime Continent (TMC). To address the issue, we utilized a three–dimensional high–resolution physical–biogeochemical ocean numerical model and applied it to simulate sea–air CO2 exchange in the region over the last decade (2010–2019). Some key features like atmospheric CO2 source signature and high sea surface pCO2 environment inside the TMC were captured by the model. Within the TMC, model results indicated strong CO2 degassing along the south of Java associated with the seasonal cycle of the upwelling system. Abundant supply of inorganic carbon during upwelling season and strong wind speed results in CO2 degassing that could reach as high as 30 gC m–2 year–1 around the area. In addition to the region acting as a full–year atmospheric CO2 source, the TMC also exhibited interannual modulation in both sea–air CO2 flux and sea surface pCO2 which can be related to the El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). Large–scale anomalous strong CO2 degassing and high sea surface pCO2 from 2015 to 2016 in response to the 2015/2016 El Niño evolution was observed and dominated by modulation within the TMC. It is further found that modulation of CO2 degassing related to IOD were confined along the west of south of Java with a higher magnitude compared with anomalies related to ENSO which shows larger spatial scale but lower in the magnitude. Study conducted here may provide insight about possible variabilities of sea–air CO2 exchange in the area that still poorly represented in many global–scale modelling and reconstruction efforts.

Biogeochemical Cycle

Ekman transport

10.5194/egusphere-2022-1067-rc2

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Absolute gravity signals at the Sakurajima volcano since 2009 through 2016

Japan Geoscience Union (2017)

Shuhei Okubo Keigo Yamamoto Masato Iguchi Yoshiyuki Tanaka Yuichi Imanishi

Source

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Deep Reflection Imaging beneath the Mizuho Plateau, East Antarctica, by SEAL-2002 Seismic Experiment

Springer eBooks (2006)

Mikiya Yamashita Hiroki Miyamachi Masaki Kanao Takeshi Matsushima Shigeru Toda

Traverse

Discontinuity (linguistics)

10.1007/3-540-32934-x_18

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Citations (7)

Absolute gravity signals at the Sakurajima volcano since 2009 through 2018

Japan Geoscience Union (2019)

Shuhei Okubo Keigo Yamamoto Masato Iguchi Yoshiyuki Tanaka Yuichi Imanishi

Source

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Comment on egusphere-2022-1067

Faisal Amri Takashi Nakamura Atsushi Watanabe Aditiya R. Kartadikaria Kazuo Nadaoka

Abstract. The lack of long–term observational data has limited research on sea–air CO₂ exchange variabilities in the Tropical Maritime Continent (TMC). To address the issue, we utilized a three–dimensional high–resolution physical–biogeochemical ocean numerical model and applied it to simulate sea–air CO₂ exchange in the region over the last decade (2010–2019). Some key features like atmospheric CO₂ source signature and high sea surface pCO₂ environment inside the TMC were captured by the model. Within the TMC, model results indicated strong CO₂ degassing along the south of Java associated with the seasonal cycle of the upwelling system. Abundant supply of inorganic carbon during upwelling season and strong wind speed results in CO₂ degassing that could reach as high as 30 gC m^–2 year^–1 around the area. In addition to the region acting as a full–year atmospheric CO₂ source, the TMC also exhibited interannual modulation in both sea–air CO₂ flux and sea surface pCO₂ which can be related to the El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). Large–scale anomalous strong CO₂ degassing and high sea surface pCO₂ from 2015 to 2016 in response to the 2015/2016 El Niño evolution was observed and dominated by modulation within the TMC. It is further found that modulation of CO₂ degassing related to IOD were confined along the west of south of Java with a higher magnitude compared with anomalies related to ENSO which shows larger spatial scale but lower in the magnitude. Study conducted here may provide insight about possible variabilities of sea–air CO₂ exchange in the area that still poorly represented in many global–scale modelling and reconstruction efforts.

Biogeochemical Cycle

Ekman transport

10.5194/egusphere-2022-1067-rc1

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Citations (0)