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| Choe, Hanjin; Dyment, Jerome. |
| Seafloor spreading magnetic anomalies formed at mid‐ocean ridges initially display strong amplitudes that decay within the first 10 million years as a result of pervasive hydrothermal circulation and alteration. The amplitudes do not vary much for older oceanic crust, suggesting that the thickening sediments hinder heat advection. Here we show, however, that a systematic loss of ~20 % in the amplitude of the anomalies arises between the outer rise and the trench on old ocean crust approaching the Japan and Kuril subduction zones. We interpret this decay as reflecting the opening of normal faults and fissures caused by extension on the outer flexural rise, and the subsequent renewed circulation of seawater into the oceanic crust, resulting in additional... |
| Tipo: Text |
Palavras-chave: Hydrothermal circulation; Marine magnetic anomaly; Subduction zone; Outer rise; Bending oceanic crust. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00614/72611/71621.pdf |
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| Klingelhoefer, Frauke; Gutscher, M. -a.; Ladage, S.; Dessa, J. -x.; Graindorge, D.; Franke, D.; Andre, Camille; Permana, H.; Yudistira, T.; Chauhan, A.. |
| The 26 December 2004 Sumatra earthquake (M-w = 9.1) initiated around 30 km depth and ruptured 1300 km of the Indo-Australian-Sunda plate boundary. During the Sumatra-OBS (ocean bottom seismometer) survey, a wide-angle seismic profile was acquired across the epicentral region. A seismic velocity model was obtained from combined travel time tomography and forward modeling. Together with reflection seismic data from the SeaCause II cruise, the deep structure of the source region of the great earthquake is revealed. Four to five kilometers of sediments overlie the oceanic crust at the trench, and the subducting slab can be imaged down to a depth of 35 km. We find a crystalline backstop 120 km from the trench axis, below the fore-arc basin. A high-velocity zone... |
| Tipo: Text |
Palavras-chave: Middle america trench; Fore arc basin; Bottom seismographic observation; Subduction zone; Crustal structure; Accretionary prism; Mantle serpentinization; Aftershock distribution; Megathrust earthquakes; Velocity structure. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00000/11155/7737.pdf |
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| Patriat, Martin; Falloon, Trevor; Danyushevsky, Leonid; Collot, Julien; Jean, Marlon M.; Hoernle, Kaj; Hauff, Folkmar; Maas, Roland; Woodhead, Jon D.; Feig, Sandrin T.. |
| The development of ideas leading to a greater understanding of subduction initiation is limited by the scarcity of present-day examples. Furthermore, the few examples identified so far unfortunately provide few insights into the nature of magmatism at the inception of subduction. Here we report new observations from the Matthew and Hunter (M&H) subduction zone, a very young subduction zone located in the South-West Pacific. Tectonics of the area show it is younger than 2 Ma, making the M&H the youngest known volcanically-active subduction system and hence providing unique insights into the earliest stages of subduction initiation. Volcanism in this area comprises an exceptionally diverse range of contemporaneously erupting magma compositions which... |
| Tipo: Text |
Palavras-chave: Subduction zone; Subduction initiation; Forearc; Ophiolites; Boninites; Adakites. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00473/58422/61077.pdf |
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| Murphy, Shane; Di Toro, G.; Romano, F.; Scala, A.; Lorito, S.; Spagnuolo, E.; Aretusini, S.; Festa, G.; Piatanesi, A.; Nielsen, S.. |
| Seismological, tsunami and geodetic observations have shown that subduction zones are complex systems where the properties of earthquake rupture vary with depth as a result of different pre-stress and frictional conditions. A wealth of earthquakes of different sizes and different source features (e.g. rupture duration) can be generated in subduction zones, including tsunami earthquakes, some of which can produce extreme tsunamigenic events. Here, we offer a geological perspective principally accounting for depth-dependent frictional conditions, while adopting a simplified distribution of on-fault tectonic pre-stress. We combine a lithology-controlled, depth-dependent experimental friction law with 2D elastodynamic rupture simulations for a Tohoku-like... |
| Tipo: Text |
Palavras-chave: Subduction zone; Megathrust; Dynamic rupture; Rock physics experiments; Tsunami earthquake. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00425/53625/54546.pdf |
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| Boucard, M; Marcaillou, B; Lebrun, Jf; Laurencin, M; Klingelhoefer, Frauke; Laigle, M; Lallemand, S; Schenini, L; Graindorge, David; Cornee, Jj; Munch, P; Philippon, M; The Antithesis 1, 3 And Garanti Scientific Teams.,. |
| Oblique collision of buoyant provinces against subduction zones frequently results in individualizing and rotating regional-scale blocks. In contrast, the collision of the Bahamas Bank against the Northeastern Caribbean Plate increased the margin convexity triggering forearc fragmentation into small-scale blocks. This deformation results in a prominent >450- km-long sequence of V-shaped basins that widens trenchward separated by elevated spurs, in the Northern Lesser Antilles (NLA, i.e. Guadeloupe to Virgin Island). In absence of deep structure imaging, various competing models were proposed to account for this faults-bounded Basins-and-Spurs System. High-resolution bathymetric and deep multichannel seismic data acquired during cruises... |
| Tipo: Text |
Palavras-chave: Margin tectonic fracturing; Northern Lesser Antilles; Oblique collision; Subduction erosion; Subduction zone; Vertical motion. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00651/76351/77343.pdf |
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