scholarly journals Azimuthal anisotropy in the Chile Ridge subduction region retrieved from ambient noise

Lithosphere ◽  
2011 ◽  
Vol 3 (6) ◽  
pp. 393-400 ◽  
Author(s):  
A. Gallego ◽  
M.P. Panning ◽  
R.M. Russo ◽  
D. Comte ◽  
V.I. Mocanu ◽  
...  
Keyword(s):  
Ambient Noise ◽  
Azimuthal Anisotropy ◽  
Ridge Subduction ◽  
Chile Ridge

scholarly journals Seismic noise tomography in the Chile ridge subduction region

2010 ◽  
Vol 182 (3) ◽  
pp. 1478-1492 ◽  
Author(s):  
A. Gallego ◽  
R. M. Russo ◽  
D. Comte ◽  
V. I. Mocanu ◽  
R. E. Murdie ◽  
...  
Keyword(s):  
Seismic Noise ◽  
Ridge Subduction ◽  
Chile Ridge

Neogene Patagonian magmatism between the rupture of the Farallon plate and the Chile Ridge subduction

2021 ◽  
pp. 103238
Author(s):  
Cristóbal Ramírez de Arellano ◽  
Mauricio Calderón ◽  
Huber Rivera ◽  
Mauricio Valenzuela ◽  
C. Mark Fanning ◽  
...  
Keyword(s):  
Ridge Subduction ◽  
Chile Ridge

Azimuthally anisotropic ambient-noise tomography using the AlpArray seismic network

2020 ◽  
Author(s):  
Emanuel Kästle ◽  
Irene Molinari ◽  
Lapo Boschi ◽  
AlpArray Working Group
Keyword(s):  
Phase Velocity ◽  
Ambient Noise ◽  
Velocity Structure ◽  
Sedimentary Basins ◽  
Shear Velocity ◽  
Velocity Model ◽  
Azimuthal Anisotropy ◽  
Seismic Network ◽  
Fast Axis ◽  
Noise Field

<p>We make use of the AlpArray Seismic Network to study the properties of the ambient-noise field and create a new 3D shear-velocity model of the Alpine crust. The latter will be used to improve our understanding of the tectonic processes that formed the Alps.</p><p>From two years of data, more than 150,000 station-station cross-correlations are extracted and used to evaluate strength and directivity of the noise field and its seasonal variations. Phase-velocity measurements for both Love and Rayleigh waves are obtained and the anisotropic phase-velocity structure is imaged. At mid-crustal levels, the strongest azimuthal anisotropy is found underneath the northern Italian Po plain and in the northern Dinarides, with strengths of 10-20% and a fast axis direction pointing NNE in Italy and NE in the Dinarides. In the western and central Alps we find an approximately NE direction and a strength of 5%; the eastern Alpine fast axis point toward the north with strengths of 2-5%.</p><p>We apply a probabilistic inversion to resolve the 3D shear-velocity structure of the crust. The homogeneous and dense station setup results in a shear-velocity model of unprecedented resolution for the uppermost 60 km of the crust underneath the entire orogen. By using data in the period range between 2 and 100s, we are able to better constrain shallow structures, such as the sedimentary basins, and to link surface-geological features to velocity variations observed at depth.</p>

Timing and origin of deformation along the Patagonian fold and thrust belt

2000 ◽  
Vol 137 (4) ◽  
pp. 345-353 ◽  
Author(s):  
M. SUÁREZ ◽  
R. DE LA CRUZ ◽  
C. M. BELL
Keyword(s):  
Continental Margin ◽  
Foreland Basin ◽  
South American ◽  
Thrust Belt ◽  
The South ◽  
Plate Convergence ◽  
Ridge Subduction ◽  
Fold And Thrust Belt ◽  
Chile Ridge ◽  
Oceanic Plates

The Andean orogeny in the Patagonian Cordillera of southern South America reflects the consequences of the Mesozoic and Cenozoic subduction of an oceanic plate beneath the South American continental margin. The geological evolution of the region has been influenced by the Eocene collision and subduction of the Farallon–Aluk Ridge and the Miocene–Recent subduction of the Chile Ridge. Another aspect of plate interaction during this period was two intervals of rapid plate convergence, one at 50–42 Ma, and the other at 25–10 Ma, between the South American and the oceanic plates. It has been proposed that the collision of the Chile Ridge with the trench was responsible for the development, at least in part, of the Patagonian fold and thrust belt. This belt extends for more than 1000 km along the eastern foothills of the southern Andes between 46° and 54° S along the southwestern rim of the Austral Basin. The interpretation of a link between subduction of the ridge and formation of the fold and thrust belt is based on assumed time coincidences between contractional tectonism and the collision of ridge segments during Middle and Late Miocene times. The main Tertiary contractional events in the Patagonian fold and thrust belt took place during latest Cretaceous–Palaeocene–Eocene and during Miocene times. Although the timing of deformation is still poorly constrained, the evidence currently available suggests that there is little or no relationship between the timing of the fold and thrust belt and the collision of ridge segments. Most if not all of the contractional tectonism pre-dated the latest episodes of ridge collision. Collision of a ridge crest with the continental margin has been active for the past 14 to 15 million years. Contrary to the suggestion of a relationship between ridge subduction and compression, the main result of this collision has been fast uplift and extensional tectonism. The initiation of the Patagonian fold and thrust belt in latest Cretaceous or early Tertiary times coincided with a fundamental change in the tectonic evolution of the Austral Basin. Throughout the Cretaceous most of this basin subsided as a broad backarc continental shelf. Only in latest Cretaceous times, and coinciding with the initiation of the fold and thrust belt, the basin underwent a transition to a retro-arc foreland basin. This change to an asymmetrically subsiding foreland basin, with an associated foreland fold and thrust belt, was related to uplift of the Andean orogenic belt in the west.

Source-side shear wave splitting and upper mantle flow in the Chile Ridge subduction region

Geology ◽  
2010 ◽  
Vol 38 (8) ◽  
pp. 707-710 ◽  
Author(s):  
R.M. Russo ◽  
A. Gallego ◽  
D. Comte ◽  
V.I. Mocanu ◽  
R.E. Murdie ◽  
...  
Keyword(s):  
Shear Wave ◽  
Upper Mantle ◽  
Shear Wave Splitting ◽  
Mantle Flow ◽  
Ridge Subduction ◽  
Wave Splitting ◽  
Chile Ridge

scholarly journals Estimation of azimuthal anisotropy in the NW Pacific from seismic ambient noise in seafloor records

2014 ◽  
Vol 199 (1) ◽  
pp. 11-22 ◽  
Author(s):  
Akiko Takeo ◽  
Donald W. Forsyth ◽  
Dayanthie S. Weeraratne ◽  
Kiwamu Nishida
Keyword(s):  
Ambient Noise ◽  
Azimuthal Anisotropy ◽  
Seismic Ambient Noise

Imaging azimuthal anisotropy in the alpine crust from ambient noise beamforming.

2021 ◽  
Author(s):  
Dorian Soergel ◽  
Helle Pedersen ◽  
Thomas Bodin ◽  
Anne Paul ◽  
Laurent Stehly
Keyword(s):  
Ambient Noise ◽  
Azimuthal Anisotropy ◽  
Noise Sources ◽  
Sks Splitting ◽  
Radial Anisotropy ◽  
Cross Correlations ◽  
The Alps ◽  
S Period ◽  
Lateral Heterogeneities

<p>Noise cross-correlations provide a good azimuthal coverage, limited only by the distribution of noise sources and the layout of the stations used. It is therefore a promising method to constrain azimuthal anisotropy. As noise cross-correlations consist mainly of surface waves, they are especially sensitive to the crust and provide good depth constraints, as opposed to SKS-splitting data that are more sensitive to the upper mantle. We use the AlpArray network as well as stations from permanent networks all across Europe to perform time-domain beamforming on noise cross-correlations. The extent and density of the AlpArray network allows us to obtain reliable measurements all across the Alps. We divide the area in smaller zones using all stations outside the zone as sources and all stations inside as a sub-array for beamforming. This allows us to estimate the quality of our measurements in a region where strong lateral heterogeneities make measurements challenging, by estimating the magnitude of bias due to heterogeneities using the cos(theta) amplitude and evaluating uncertainties with bootstrap. This way, we measure Rayleigh wave azimuthal anisotropy in several period bands between 15 s and 60 s period. Inversion of dispersion curves in specific areas allows us to constrain the depth of the observed anisotropy. The results are broadly similar to results from SKS-splitting as they are generally parallel to the mountain belt. However, we observe lower anisotropy at short periods (40 seconds and less) in the Alps themselves than in surrounding regions. We also observe several structures in the crust that are not observed with SKS-splitting data. The most striking is a strong and spatially coherent NE-oriented anisotropy to the NW of the Alps that is possibly related to Variscan inheritance (at 40 seconds and less, in the upper and lower crust).  In the Northern Apennines, we observe anisotropy perpendicular to the belt at 30 s period (middle crust) that correlates well with an area of strong radial anisotropy recently observed by Alder et al (in review) at 30 km depth. </p>

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