Nankai Forearc Structural and Seismogenic Segmentation Caused by a Magmatic Intrusion off the Kii Peninsula
Abstract The causes for forearc basin and megathrust rupture zone segmentation are controversial. The Nankai forearc, Japan, is separated into five domains based on topography: Enshu, Kumano, Muroto, Tosa, and Hyuga. The boundaries of these domains correspond to the rupture limits of large earthquak...
| 主要な著者: | , , , , , , , |
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| フォーマット: | 論文 |
| 言語: | English |
| 出版事項: |
Wiley
2022-08-01
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| シリーズ: | Geochemistry, Geophysics, Geosystems |
| 主題: | |
| オンライン･アクセス: | https://doi.org/10.1029/2022GC010331 |
| _version_ | 1827771746516729856 |
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| author | G. Kimura Y. Nakamura K. Shiraishi G. Fujie S. Kodaira T. Tsuji R. Fukuchi A. Yamaguchi |
| author_facet | G. Kimura Y. Nakamura K. Shiraishi G. Fujie S. Kodaira T. Tsuji R. Fukuchi A. Yamaguchi |
| author_sort | G. Kimura |
| collection | DOAJ |
| description | Abstract The causes for forearc basin and megathrust rupture zone segmentation are controversial. The Nankai forearc, Japan, is separated into five domains based on topography: Enshu, Kumano, Muroto, Tosa, and Hyuga. The boundaries of these domains correspond to the rupture limits of large earthquakes. We examined the geologic structure of the boundary region between the Kumano and Muroto domains off the Kii Peninsula using multichannel seismic reflection data to evaluate the role of upper plate composition in controlling segmentation. The results suggest that thick cover sediments and underlying accretionary prism are obliquely thrust landward over the igneous basement complex rock in the region of offshore of Cape Shionomisaki and separate the forearc basin. The igneous basement complex rocks directly overlying the plate interface in the hypocentral regions of 1944 Tonankai and 1946 Nankai earthquakes. The 1944 earthquake originated at the base of the complex, and the rupture extent slipped past its basement boundary, whereas the 1946 event nucleated at the updip boundary of the basement complex. The dense igneous rocks might have worked as a heavily loaded barrier on the seismogenic megathrust and separated the rupture area of both the earthquakes. Upper plate geology may be an important factor in controlling seismogenesis in the Nankai Trough and may serve as an example for understanding the controls on megathrust slip in other subduction zones. |
| first_indexed | 2024-03-11T12:58:37Z |
| format | Article |
| id | doaj.art-805f3cd196cd4b08a67262ddae538f68 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:58:37Z |
| publishDate | 2022-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-805f3cd196cd4b08a67262ddae538f682023-11-03T16:55:35ZengWileyGeochemistry, Geophysics, Geosystems1525-20272022-08-01238n/an/a10.1029/2022GC010331Nankai Forearc Structural and Seismogenic Segmentation Caused by a Magmatic Intrusion off the Kii PeninsulaG. Kimura0Y. Nakamura1K. Shiraishi2G. Fujie3S. Kodaira4T. Tsuji5R. Fukuchi6A. Yamaguchi7Research Institute for Marine Geodynamics Japan Agency for Marine Earth Science and Technology Yokohama‐city JapanResearch Institute for Marine Geodynamics Japan Agency for Marine Earth Science and Technology Yokohama‐city JapanResearch Institute for Marine Geodynamics Japan Agency for Marine Earth Science and Technology Yokohama‐city JapanResearch Institute for Marine Geodynamics Japan Agency for Marine Earth Science and Technology Yokohama‐city JapanResearch Institute for Marine Geodynamics Japan Agency for Marine Earth Science and Technology Yokohama‐city JapanDepartment of Systems Innovation Faculty of Engineering The University of Tokyo Tokyo JapanNaruto University of Education Takashima JapanDepartment of Ocean Floor Geoscience Atmosphere and Ocean Research Institute The University of Tokyo Kashiwa‐shi JapanAbstract The causes for forearc basin and megathrust rupture zone segmentation are controversial. The Nankai forearc, Japan, is separated into five domains based on topography: Enshu, Kumano, Muroto, Tosa, and Hyuga. The boundaries of these domains correspond to the rupture limits of large earthquakes. We examined the geologic structure of the boundary region between the Kumano and Muroto domains off the Kii Peninsula using multichannel seismic reflection data to evaluate the role of upper plate composition in controlling segmentation. The results suggest that thick cover sediments and underlying accretionary prism are obliquely thrust landward over the igneous basement complex rock in the region of offshore of Cape Shionomisaki and separate the forearc basin. The igneous basement complex rocks directly overlying the plate interface in the hypocentral regions of 1944 Tonankai and 1946 Nankai earthquakes. The 1944 earthquake originated at the base of the complex, and the rupture extent slipped past its basement boundary, whereas the 1946 event nucleated at the updip boundary of the basement complex. The dense igneous rocks might have worked as a heavily loaded barrier on the seismogenic megathrust and separated the rupture area of both the earthquakes. Upper plate geology may be an important factor in controlling seismogenesis in the Nankai Trough and may serve as an example for understanding the controls on megathrust slip in other subduction zones.https://doi.org/10.1029/2022GC010331Nankai Troughforearc basinmegathrustsubductionearthquakesegmentation |
| spellingShingle | G. Kimura Y. Nakamura K. Shiraishi G. Fujie S. Kodaira T. Tsuji R. Fukuchi A. Yamaguchi Nankai Forearc Structural and Seismogenic Segmentation Caused by a Magmatic Intrusion off the Kii Peninsula Geochemistry, Geophysics, Geosystems Nankai Trough forearc basin megathrust subduction earthquake segmentation |
| title | Nankai Forearc Structural and Seismogenic Segmentation Caused by a Magmatic Intrusion off the Kii Peninsula |
| title_full | Nankai Forearc Structural and Seismogenic Segmentation Caused by a Magmatic Intrusion off the Kii Peninsula |
| title_fullStr | Nankai Forearc Structural and Seismogenic Segmentation Caused by a Magmatic Intrusion off the Kii Peninsula |
| title_full_unstemmed | Nankai Forearc Structural and Seismogenic Segmentation Caused by a Magmatic Intrusion off the Kii Peninsula |
| title_short | Nankai Forearc Structural and Seismogenic Segmentation Caused by a Magmatic Intrusion off the Kii Peninsula |
| title_sort | nankai forearc structural and seismogenic segmentation caused by a magmatic intrusion off the kii peninsula |
| topic | Nankai Trough forearc basin megathrust subduction earthquake segmentation |
| url | https://doi.org/10.1029/2022GC010331 |
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