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| Tsang-hin-sun, Eve; Royer, Jean-yves; Perrot, Julie. |
| Volcanic and tectonic events are the main processes involved in the generation of the oceanic crust and responsible for the seismicity associated with seafloor spreading. To monitor this activity, usually not or poorly detected by land-based seismological stations, we deployed from February 2012 to February 2013 a network of autonomous hydrophones to compare the behaviour of the ultraslow-spreading Southwest (SWIR) with that of the intermediate-spreading Southeast Indian ridges (SEIR). The rate of seismicity is similar for both ridges, suggesting that there is no systematic relationship between seismicity and spreading rates. The along-axis distribution of the seismic events, however, does differ, reflecting the rate-dependence of accretion modes.... |
| Tipo: Text |
Palavras-chave: Seismicity and tectonics; Acoustic properties; Mid-ocean ridge processes; Indian Ocean. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00340/45165/44559.pdf |
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| Klingelhoefer, Frauke; Evain, Mikael; Afilhado, A.; Rigoti, Caesar; Loureiro, Afonso; Alves, D.; Lepretre, Angelique; Moulin, Maryline; Schnurle, Philippe; Benabdellouahed, Massinissa; Baltzer, Agnes; Rabineau, Marina; Feld, Aurelie; Viana, A.; Aslanian, Daniel. |
| During the Sanba (Santos basin seismic transect) experiment in 2010–2011, a 380-km-long combined wide-angle and reflection seismic profile has been acquired using 30 ocean-bottom seismometers, a 4.5 km seismic streamer and a 8900 in.3 airgun array. The Sanba 3 profile crosses the southern flank of the Sao Paulo Plateau, the Sao Paulo Ridge and the easternmost Santos Basin in an east–west direction. Its eastern end is located on undisturbed oceanic crust. Tomographic and forward modelling of the wide-angle seismic data reveals that the sedimentary thickness is variable with only 1–2 km on top of the ridge and thickening to 4–5 km in the basin. Crustal thickness at the ridge is about 18 km and the relative layer thickness and velocity gradients indicate a... |
| Tipo: Text |
Palavras-chave: Controlled source seismology; Seismic tomography; Mid-ocean ridge processes; Continental margins: divergent; Continental tectonics: extensional; Crustal structure; South America. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00242/35296/33826.pdf |
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| Royer, J. -y.; Chateau, R.; Dziak, R. P.; Bohnenstiehl, D. R.. |
| This paper presents the results from the Deflo-hydroacoustic experiment in the Southern Indian Ocean using three autonomous underwater hydrophones, complemented by two permanent hydroacoustic stations. The array monitored for 14 months, from November 2006 to December 2007, a 3000 x 3000 km wide area, encompassing large segments of the three Indian spreading ridges that meet at the Indian Triple Junction. A catalogue of 11 105 acoustic events is derived from the recorded data, of which 55 per cent are located from three hydrophones, 38 per cent from 4, 6 per cent from five and less than 1 per cent by six hydrophones. From a comparison with land-based seismic catalogues, the smallest detected earthquakes are m(b) 2.6 in size, the range of recorded magnitudes... |
| Tipo: Text |
Palavras-chave: Hydrogeophysics; Acoustic properties; Mid-ocean ridge processes; Indian Ocean. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00351/46249/46101.pdf |
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| Ahmed, Abdulhakim; Doubre, Cecile; Leroy, Sylvie; Kassim, Mohamed; Keir, Derek; Abayazid, Ahmadine; Julie, Perrot; Laurence, Audin; Vergne, Jerome; Alexandre, Nercessian; Jacques, Eric; Khanbari, Khaled; Sholan, Jamal; Rolandone, Frederique; Al-ganad, Ismael. |
| In November 2010, intense seismic activity including 29 events with a magnitude above 5.0, started in the western part of the Gulf of Aden, where the structure of the oceanic spreading ridge is characterized by a series of N115 degrees-trending slow-spreading segments set within an EW-trending rift. Using signals recorded by permanent and temporary networks in Djibouti and Yemen, we located 1122 earthquakes, with a magnitude ranging from 2.1 to 5.6 from 2010 November 1 to 2011 March 31. By looking in detail at the space-time distribution of the overall seismicity, and both the frequency and the moment tensor of large earthquakes, we re-examine the chronology of this episode. In addition, we also interpret the origin of the activity using high-resolution... |
| Tipo: Text |
Palavras-chave: Earthquake source observations; Seismicity and tectonics; Mid-ocean ridge processes; Transform faults; Submarine tectonics and volcanism; Dynamics: seismotectonics. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00639/75087/75528.pdf |
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