Article
Chemistry, Analytical
Dan Liu, Ting Yang, Yizhi Wang, Yuechu Wu, Xinfeng Huang
Summary: This paper presents a new broadband ocean bottom seismograph (OBS) called Pankun, developed by the SUSTech OBS lab, which has several key features that distinguish it from traditional OBS instruments. These features include a unique shielding structure to minimize current-induced noise, a compact gimbal for accurate leveling, and low power consumption for extended operation on the seafloor. The design and testing of Pankun's primary components are thoroughly described in this paper, and it has been successfully tested in the South China Sea, demonstrating its ability to record high-quality seismic data. The anti-current shielding structure of Pankun OBS has the potential to improve low-frequency signals, particularly on the horizontal components, in seafloor seismic data.
Article
Environmental Sciences
Qianqian Li, Yaxin Liu, Lei Xing, Xiao Han, Yuzhao Lin, Jin Zhang, Hongmao Zhang
Summary: This study investigates the characteristics of ambient noise in the Chukchi Sea area under different frequency bands and environmental settings. By comparing the results with global noise models, the study provides insights into the distribution patterns and sources of ambient noise in this region.
Article
Geochemistry & Geophysics
Liqun Cheng, Yinxia Fang, Xiongwei Niu, Tingzi Li, Chongzhi Dong, Yanghui Zhao, Hao Hu, Fansheng Kong, Pingchuan Tan, Aiguo Ruan, Shaoping Lu, Jianke Fan, Hafeez Jeofry Muhammad, Weiwei Ding, Jiabiao Li, Xinguang Du
Summary: The South China Sea is a typical marginal sea basin that has undergone asymmetric spreading, ridge jumps, and intense volcanic activity. The results of a seismic experiment conducted in the South China Sea basin indicate that the Zhongnan fault zone played a crucial role in the expansion of the basin and there was oblique magma migration during post-spreading volcanism.
Article
Environmental Sciences
Angelo De Santis, Massimo Chiappini, Giuditta Marinaro, Sergio Guardato, Fabio Conversano, Giuseppe D'Anna, Domenico Di Mauro, Vanessa Cardin, Roberto Carluccio, Sante Francesco Rende, Raffaele Giordano, Lorenzo Rossi, Francesco Simeone, Emanuele Giacomozzi, Gioacchino Fertitta, Antonio Costanza, GianPaolo Donnarumma, Rosario Riccio, Giuseppe Siena, Giuseppe Civitarese
Summary: The InSEA project aims to consolidate and strengthen the EMSOS ERIC and its related infrastructure. The project is upgrading marine infrastructure in southern Italy to support the observation activities of EMSOS ERIC. It is developed based on six implementation objectives and involves several Italian national research institutions.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Geochemistry & Geophysics
Asdis Benediktsdottir, Olafur Gudmundsson, Ka Lok Li, Bryndis Brandsdottir
Summary: Research shows that volcanic eruptions in Iceland are generally preceded by an increase in tremor levels, which do not have a clear onset like earthquakes. During the Eyjafjallajokull summit eruption, volcanic tremor frequencies ranged between 0.5 and 10 Hz, and the power variations of the tremor with distance from the eruption site indicate that surface waves dominate the tremor waveform content in the 0.5-2 Hz frequency range. The pattern of radiated wave energy from the tremor source varied with time, defining ten different epochs during the eruption.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Environmental Sciences
Domenico Patane, Giuseppina Tusa, William Yang, Antonio Astuti, Antonio Colino, Antonio Costanza, Giuseppe D'Anna, Sergio Di Prima, Gioacchino Fertitta, Salvatore Mangiagli, Claudio Martino, Orazio Torrisi
Summary: This article describes the first dense real-time urban seismic-accelerometric network in Italy, called OSU-CT, located in the historic center of Catania. OSU-CT aims to rapid assess earthquake-induced damage and test an on-site earthquake early warning system. The network is based on low-cost instrumentation and has already deployed 20 stations in significant historic public buildings. Through a test earthquake, the network has provided reliable information on urban seismic activity and ground motion distribution.
Article
Geosciences, Multidisciplinary
Hajime Shiobara, Aki Ito, Hiroko Sugioka, Masanao Shinohara, Toshinori Sato
Summary: The research team has developed a series of ocean bottom seismometers since 1999 and conducted various practical observations to create a new research field of ocean bottom broadband seismology. They aim to establish a geodetic observation network on the seafloor using these instruments, and have conducted some tilt observations, the feasibility of which needs further verification.
FRONTIERS IN EARTH SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Genggeng Wen, Kuiyuan Wan, Shaohong Xia, Huilong Xu, Chaoyan Fan, Jinghe Cao
Summary: The study focused on the travel-time inversion method of converted S-waves to determine the crustal S-wave velocity along profile NS5. The results showed that the Vs and Vp/Vs of the crust were 3.0-4.4 km/s and 1.71-1.80, respectively. The inversion model had a similar trend with the forward model in terms of velocity and Vp/Vs ratios, and revealed detailed crustal structures including magma conduits.
APPLIED SCIENCES-BASEL
(2021)
Article
Geosciences, Multidisciplinary
Bin Liu, JianYu Huang, WenBin Jiang, WeiWei Wang, Li Yang
Summary: The use of ocean bottom seismometers allows for the study of cold seeps by recording sub-seafloor fluid migration events. A four-component Ocean Bottom Seismometer was deployed at the Haima cold seep site in the South China Sea to monitor and distinguish different types of events. By analyzing the collected data, it was found that the occurrence of short duration events (SDEs) was relatively low, indicating a less active fluid migration and gas seepage at the Haima site compared to other cold seep regions. This finding expands the understanding of cold seep-related SDEs in the South China Sea.
EARTH AND PLANETARY PHYSICS
(2023)
Article
Geosciences, Multidisciplinary
Tiziana Sgroi, Alina Polonia, Laura Beranzoli, Andrea Billi, Alessandro Bosman, Antonio Costanza, Marco Cuffaro, Giuseppe D'Anna, Mariagrazia De Caro, Maria Di Nezza, Gioacchino Fertitta, Francesco Frugoni, Luca Gasperini, Stephen Monna, Caterina Montuori, Lorenzo Petracchini, Patrizio Petricca, Stefania Pinzi, Andrea Ursino, Carlo Doglioni
Summary: The study focuses on seismogenic structures in the Ionian Sea potential sources of medium-high magnitude earthquakes and highlights the importance of marine studies with Ocean Bottom Seismometers in geologically active areas prone to high seismic risk.
FRONTIERS IN EARTH SCIENCE
(2021)
Article
Geochemistry & Geophysics
Yuki Kawano, Takehi Isse, Akiko Takeo, Hitoshi Kawakatsu, Manabu Morishige, Hajime Shiobara, Nozomu Takeuchi, Hiroko Sugioka, YoungHee Kim, Hisashi Utada, Sang-Mook Lee
Summary: By analyzing seismic records collected at the oldest Pacific seafloor, we revealed the structural characteristics and evolution of the Pacific plate. Our findings suggest the occurrence of reheating process beneath the oldest lithosphere and the existence of different azimuthal anisotropy in different regions of the Pacific plate. These results provide insights into the complex evolution dynamics of the Pacific plate.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Environmental Sciences
Brianna Corsa, Magali Barba-Sevilla, Kristy Tiampo, Charles Meertens
Summary: Establishing a reliable observation system to provide early warnings of volcanic eruptions is crucial for the approximately 800 million people living near volcanoes worldwide. By combining Global Navigation Satellite System (GNSS) and satellite Synthetic Aperture Radar (SAR) data, we are able to obtain accurate information about ground motions and volcanic eruptions. This method can be replicated in other regions where GNSS and SAR data overlap.
Article
Geochemistry & Geophysics
Li ZiZheng, Qiu XueLin, He EnYuan, Zhang HaoYu, Wang Qiang
Summary: This study reveals the complicated tectonic and subduction dynamics of the Mariana Trench through seismic profiles and gravity modeling. It identifies a wedge-shaped forearc crust and subduction erosion, and determines the crustal thickness and interface positions between plates. Gravity modeling also indicates serpentinization in the uppermost mantle of the downgoing plate.
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
(2023)
Article
Geochemistry & Geophysics
Pengfei Yu, Mingzhi Chu, Jiameng Jiang
Summary: Proper decomposition of P- and S-waves is crucial for multicomponent ocean bottom seismic data processing. Separate calibration filters are designed to accurately calibrate the kinematic and dynamic characteristics of particle velocity (or displacement) components, allowing for appropriate adjustment of energy distribution within each component.
PURE AND APPLIED GEOPHYSICS
(2023)
Article
Geochemistry & Geophysics
Zhang HaoYu, Qiu XueLin, Wang Qiang, Huang HaiBo, Zhao MingHui
Summary: The analysis and simulation of converted seismic shear wave phases recorded by active-source Ocean Bottom Seismometers provide accurate constraints on subsurface structures and lithological compositions, facilitating research on detailed crustal structures and tectonic affinity. By processing and analyzing seismic shear wave phases from OBS2013-3 traversing the Xisha Block, the South China Sea margin, dominant P-S conversion interfaces of sedimentary basement, seafloor, and the Moho are identified in radial components. A series of PPS and PSS type converted shear wave phases are observed, with a maximum offset of 130 km, potentially laying a solid foundation for subsequent 2-D shear wave velocity or Poisson's ratio modeling and crustal composition analysis.
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
(2021)
Article
Geosciences, Multidisciplinary
Kiyoshi Baba, Noriko Tada, Hiroshi Ichihara, Yozo Hamano, Hiroko Sugioka, Takao Koyama, Akimichi Takagi, Minoru Takeo
EARTH PLANETS AND SPACE
(2020)
Article
Geochemistry & Geophysics
Nozomu Takeuchi, Hitoshi Kawakatsu, Hajime Shiobara, Takehi Isse, Hiroko Sugioka, Aki Ito, Hisashi Utada
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2020)
Article
Geosciences, Multidisciplinary
Yuki Kawano, Takehi Isse, Akiko Takeo, Hitoshi Kawakatsu, Daisuke Suetsugu, Hajime Shiobara, Hiroko Sugioka, Aki Ito, Yasushi Ishihara, Satoru Tanaka, Masayuki Obayashi, Takashi Tonegawa, Junko Yoshimitsu
GEOPHYSICAL RESEARCH LETTERS
(2020)
Article
Geosciences, Multidisciplinary
Hajime Shiobara, Aki Ito, Hiroko Sugioka, Masanao Shinohara, Toshinori Sato
Summary: The research team has developed a series of ocean bottom seismometers since 1999 and conducted various practical observations to create a new research field of ocean bottom broadband seismology. They aim to establish a geodetic observation network on the seafloor using these instruments, and have conducted some tilt observations, the feasibility of which needs further verification.
FRONTIERS IN EARTH SCIENCE
(2021)
Article
Geochemistry & Geophysics
HyeJeong Kim, Hitoshi Kawakatsu, Takeshi Akuhara, Masanao Shinohara, Hajime Shiobara, Hiroko Sugioka, Ryota Takagi
Summary: This study presents reflectivity images of the northeast Japan subduction zone continuous across the ocean and land, overcoming challenges related to noise level and seafloor sediment effects. The use of ocean bottom seismometer data has allowed for better imaging and understanding of the dynamics of the region.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Yoshio Fukao, Tatsuya Kubota, Hiroko Sugioka, Aki Ito, Takashi Tonegawa, Hajime Shiobara, Mikiya Yamashita, Tatsuhiko Saito
Summary: The study deployed ocean bottom pressure gauges at the Izu-Bonin Trench and observed that subduction mainly occurs through aseismic slip. Two much larger aseismic slip events were detected near a Mw6.0 thrust earthquake, with the total moment 17 times larger than that of the mainshock. This kind of slip may represent a transitional regime in the subduction zone, where slow slip events are expected to occur near its boundaries with stable sliding and unstable seismic slip regimes.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geosciences, Multidisciplinary
Tatsuya Kubota, Tatsuhiko Saito, Yoshio Fukao, Hiroko Sugioka, Aki Ito, Takashi Tonegawa, Hajime Shiobara, Mikiya Yamashita
Summary: On September 1, 2015, an M-w 5.9 interplate earthquake near the Bonin Trench generated a tsunami. In situ ocean-bottom absolute pressure gauges observed the tsunami generation field and proposed a method to synthesize pressure changes, successfully estimating the finite fault model and rupture duration solely from the APG data, indicating characteristics of a tsunami earthquake. The study suggests that in situ APGs have the potential to reveal the source process of earthquakes, essential for understanding seismotectonics in subduction zones.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Multidisciplinary Sciences
Masayuki Obayashi, Junko Yoshimitsu, Daisuke Suetsugu, Hajime Shiobara, Hiroko Sugioka, Aki Ito, Takehi Isse, Yasushi Ishihara, Satoru Tanaka, Takashi Tonegawa
Summary: The study revealed high-velocity and low-velocity anomalies in the mantle structure beneath the equatorial Melanesian region, potentially associated with the unique tectonic features where an immense oceanic plateau, a volcanic chain, and subduction zones meet. These anomalies may be linked to the thick lithosphere of the Ontong Java Plateau, remnant dipping Pacific slab, stagnant Pacific slab, and sheet-like upwelling in the upper mantle.
SCIENTIFIC REPORTS
(2021)
Article
Geochemistry & Geophysics
Yasunori Sawaki, Yusuke Yamashita, Shukei Ohyanagi, Emmanuel Soliman M. Garcia, Aki Ito, Hiroko Sugioka, Tsutomu Takahashi, Masanao Shinohara, Yoshihiro Ito
Summary: This study evaluates the seafloor ambient noise environment that varies with the water depth based on a correction analysis of the horizontal sensor orientation for ocean-bottom seismographs. The results show that shallow water areas have higher uncertainty in sensor orientation, poorer measurement quality, and higher noise levels, which are affected by low-frequency waves and ocean currents.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Yuki Kawano, Takehi Isse, Hitoshi Kawakatsu, Hajime Shiobara, Nozomu Takeuchi, Hiroko Sugioka, YoungHee Kim, Hisashi Utada, Sang-Mook Lee
Summary: We modified existing noise reduction methods to effectively remove tilt and compliance noise from low-frequency seismograms recorded by Japanese broadband ocean-bottom seismometers (BBOBSs) deployed in the western Pacific seafloor. By estimating noise transfer functions, we were able to reduce the noise levels by up to 20 dB at frequencies below 0.03 Hz. Our findings demonstrate that using a constant transfer function is appropriate for reducing tilt noise in Japanese BBOBSs equipped with the CMG-3T sensor.
BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA
(2023)
Article
Geochemistry & Geophysics
Haruka Nagai, Nozomu Takeuchi, Hitoshi Kawakatsu, Hajime Shiobara, Takehi Isse, Hiroko Sugioka, Aki Ito, Hisashi Utada
Summary: This article presents a method for inverting the seismic structures of the oceanic lithosphere-asthenosphere system, which is crucial for understanding plate tectonics. By combining envelope-fitting and waveform inversion techniques, the study successfully obtained a continuous structure model from the crust to the asthenosphere, improving the resolution in the asthenosphere.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geosciences, Multidisciplinary
Aki Ito, Hajime Shiobara, Matthew Miller, Hiroko Sugioka, Javier Ojeda, Carlos Tassara, Masanao Shinohara, Masataka Kinoshita, Hikaru Iwamori
Summary: Seafloor seismic observations were conducted twice near the Chile Triple Junction to examine crustal activities associated with hot ridge subduction. The most recent seismic observation from January 2019 to January 2021 was presented, revealing hypocenter location, magnitude, and focal mechanisms of local earthquakes. A total of over 2100 local earthquakes were detected, occurring along the Chile Ridge and the Darwin Fracture Zone with magnitudes ranging from -0.3 to 5.0.
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
(2023)
Article
Geochemistry & Geophysics
Nozomu Takeuchi, Takehi Isse, Hitoshi Kawakatsu, Hajime Shiobara, Hiroko Sugioka, Aki Ito, Hisashi Utada, Tomoaki Yamada
Summary: We analyze active and passive seismic observations to study the olivine fabrics in the oceanic lithosphere. By analyzing active-source data and teleseismic Pn waves, we observe a skewed azimuthal dependence of the Pn velocity with a large peak-to-peak amplitude of about 12%, which is explained by the direction of crystallographic axes of A-type olivine. In contrast, D-type olivine cannot explain the observations. This study suggests that secondary deformation and recrystallization in the older Pacific may be responsible for the complex seismic anisotropy in the study region.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
Yuki Kawano, Takehi Isse, Akiko Takeo, Hitoshi Kawakatsu, Manabu Morishige, Hajime Shiobara, Nozomu Takeuchi, Hiroko Sugioka, YoungHee Kim, Hisashi Utada, Sang-Mook Lee
Summary: By analyzing seismic records collected at the oldest Pacific seafloor, we revealed the structural characteristics and evolution of the Pacific plate. Our findings suggest the occurrence of reheating process beneath the oldest lithosphere and the existence of different azimuthal anisotropy in different regions of the Pacific plate. These results provide insights into the complex evolution dynamics of the Pacific plate.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Environmental Sciences
Takehi Isse, Daisuke Suetsugu, Akira Ishikawa, Hajime Shiobara, Hiroko Sugioka, Aki Ito, Yuki Kawano, Kazunori Yoshizawa, Yasushi Ishihara, Satoru Tanaka, Masayuki Obayashi, Takashi Tonegawa, Junko Yoshimitsu
Summary: Research shows that the lithosphere-asthenosphere boundary beneath the Ontong Java Plateau is approximately 40 km deeper than beneath the surrounding seafloor, suggesting it has deepened due to the underplating of dehydrated material during the formation of the plateau by a thermochemical mantle plume. Analysis indicates that the lithosphere beneath the Ontong Java Plateau is thickened by up to 40 km compared to the surrounding ocean floor, indicating it formed through the ascent of a mantle plume.
COMMUNICATIONS EARTH & ENVIRONMENT
(2021)