Elucidating the water content in the oceanic mantle using the ocean bottom seismometers

使用海底地震仪阐明大洋地幔中的水含量

• 批准号: 20J22082
• 负责人: KIM Hye Jeong
• 金额: $ 1.79万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for JSPS Fellows
• 财政年份: 2020
• 资助国家: 日本
• 起止时间: 2020-04-24 至 2023-03-31
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-20J22082/
• 关键词: 沈み込み帯; レシーバー関数; 海底地震観測; 堆積層; 地震波速度構造; スラブ; レシーバー関数

Our research aims to elucidate the hydrated regions under the Pacific plate of various ages and the subduction beneath Japan by locating low-velocity zones with in situ observations. However, the ocean bottom seismometer (OBS) records were difficult to use to gain a reliable analysis. The highly complex record due to the structure (water and slow velocity sediment) was a challenge. This research aims to exactly understand the challenges and further present methods that can overcome the difficulties.In the second year of FY2021, our work that discusses the effects of slow seafloor sediment and suggests a way to overcome the influence using the data in off Tohoku region has been published in an international journal. The work shows the low-velocity zone of the subduction zone extends beneath the shallow depths than previously reported. To discuss the variability along the trench, we collected additional OBS arrays in the off Aomori and off Ibaraki regions to extend the imaging region. The data has been pre-processed using active source records for determining component azimuths of the OBSs.In addition, a method to constrain seafloor sediment structures using passive records is developed. Research progress during FY2020 and 2021 helped us to realize that identifying sediment phases in the OBS records is important to do a structural analysis of deeper depths of 100 km. During this year, we attempted to use body waves to constrain sediment structures in high resolution and succeeded. The result of this work is planned to be presented at conferences in FY2022.

我们的研究旨在通过现场观测定位低速带，阐明不同时代的太平洋板块下方的水合区域以及日本下方的俯冲带。然而，海底地震仪（OBS）记录很难用来获得可靠的分析。由于结构（水和慢速沉积物）而产生的高度复杂的记录是一个挑战。本研究旨在准确理解挑战并进一步提出克服困难的方法。在 2021 财年的第二年，我们的工作讨论了缓慢海底沉积物的影响，并利用东北地区的数据提出了克服影响的方法已发表在国际期刊上。这项工作表明，俯冲带的低速区延伸到比之前报道的更浅的深度之下。为了讨论沿海沟的变化，我们在青森县和茨城县附近收集了额外的 OBS 阵列，以扩展成像区域。使用主动源记录对数据进行预处理，以确定 OBS 的分量方位角。此外，还开发了一种使用被动记录约束海底沉积物结构的方法。 2020 财年和 2021 财年的研究进展帮助我们认识到，识别 OBS 记录中的沉积物相对于进行 100 公里更深的结构分析非常重要。今年，我们尝试利用体波以高分辨率约束沉积物结构并取得了成功。这项工作的结果计划在 2022 财年的会议上公布。

项目成果

Receiver Function Imaging of the Amphibious NE Japan Subduction Zone--Effects of Low-Velocity Sediment Layer

日本东北俯冲带两栖接收函数成像--低速沉积层的影响

• DOI: 10.1029/2021jb021918
• 发表时间: 2021
• 作者: HyeJeong Kim; Hitoshi Kawakatsu; Takeshi Akuhara; Masanao Shinohara; Hajime Shiobara; Hiroko Sugioka; Ryota Takagi
• 通讯作者: Ryota Takagi

Receiver function imaging of the amphibious NE Japan subduction zone - effects of low-velocity sediment layer -

日本东北部两栖俯冲带的接收函数成像-低速沉积层的影响-

• 发表时间: 2021
• 作者: HyeJeong Kim; Hitoshi Kawakatsu; Takeshi Akuhara; Masanao Shinohara; Hajime Shiobara; Hiroko Sugioka; Ryota Takagi
• 通讯作者: Ryota Takagi

Receiver Function Imaging of the Amphibious NE Japan Subduction Zone: Effects of Low-Velocity Sediment Layers

日本东北部俯冲带两栖接收函数成像：低速沉积层的影响

• 发表时间: 2021
• 作者: HyeJeong Kim; Hitoshi Kawakatsu; Takeshi Akuhara; Masanao Shinohara; Hajime Shiobara; Hiroko Sugioka; Ryota Takagi
• 通讯作者: Ryota Takagi

Towards continuous seismic imaging from offshore to land along the Japan trench : effects of offshore structures (sediment layers and lateral heterogeneities)

沿着日本海沟从近海到陆地的连续地震成像：近海结构的影响（沉积物层和横向不均匀性）

• 发表时间: 2020
• 作者: HyeJeong Kim; Hitoshi Kawakatsu; Takeshi Akuhara
• 通讯作者: Takeshi Akuhara