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Facultad de Ciencias Astronomicas y Geofısicas, Universidad Nacional de La Plata, La Plata, Argentina.
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- PublicationRestrictedDepth dependent seismic scattering attenuation in the Nuevo Cuyo region (southern central Andes)(2009-12-29)
; ; ; ; ; ; ;Badi, G.; Facultad de Ciencias Astronomicas y Geofısicas, Universidad Nacional de La Plata, La Plata, Argentina. ;Del Pezzo, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Ibanez, J. M.; Instituto Andaluz de Geofısica, Universidad de Granada, Granada, Spain ;Bianco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Sabbione, N.; Facultad de Ciencias Astronomicas y Geofısicas, Universidad Nacional de La Plata, La Plata, Argentina. ;Araujo, M.; Instituto Nacional de Prevencion Sısmica, San Juan, Argentina.; ; ; ; ; In the present work we separated intrinsic from scattering attenuation coefficients both for the crust and the upper mantle in the tectonically highly active areas of the Southern-Central Andes - Nuevo Cuyo region, analyzing two groups of earthquakes, well separated in depth. This region is characterized by the presence of flat subduction. We apply MLTWA (Multiple Lapse Time Window Analysis), coda normalization and Q-coda techniques to measure the scattering and intrinsic attenuation coefficient and the total Q for S waves. We find that intrinsic attenuation does not decrease with depth whereas scattering attenuation is higher in the crust than in the upper mantle, and that intrinsic attenuation predominates over scattering attenuation. We interpret this observation in terms of the release of water and other fluids into the overlying lithosphere due to the dynamics of the subduction process, in agreement with most of the prevalent geodynamic models.201 27 - PublicationRestrictedSeismotectonic features from accurate hypocentre locations in southern central Andes (western Argentina)(2012)
; ; ; ; ; ; ; ;Scarfì, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Raffaele, R.; Dipartimento di Scienze Geologiche, Università di Catania, Italy ;Badi, G.; Facultad de Ciencias Astronómicas y Geofisicas, Universidad Nacional de La Plata, La Plata, Argentina ;Ibanez, J. M.; Instituto Andaluz de Geofisica, Universidad de Granada, Granada, Spain ;Imposa, S.; Dipartimento di Scienze Geologiche, Università di Catania, Italy ;Araujo, M.; Instituto Nacional de Prevención Sısmica, San Juan, Argentina ;Sabbione, N.; Facultad de Ciencias Astronómicas y Geofisicas, Universidad Nacional de La Plata, La Plata, Argentina; ; ; ; ; ; A local seismic network, over a five-year period, recorded about 450 earthquakes in western Argentina. In this region, the geodynamics is controlled by the subduction of the Nazca plate beneath the South American lithosphere, which is characterised here by a sub-horizontal path before reassuming its downward descent. As accurate earthquake locations are of primary importance when studying the seismicity of a given area, events recorded by the local seismic network enable in-depth investigations into seismo-tectonic patterns, allowing to improve the earthquake source characterization and knowledge on the ongoing seismo-tectonics of the region. To this end, we performed a simultaneous 1-D inversion of both the velocity structure and the hypocentre location. The minimum 1-D model obtained is complemented by station corrections which lead to a first insight into the deeper 3-D structure. In addition, stability tests were performed to verify the robustness of our earthquake location results. They reveal a fairly stable hypocentre determination, demonstrating that the locations obtained by the inversion process are not systematically biased. The results show that Sierra Pie de Palo is characterised by a crustal seismogenic structure, dipping west and extending from its eastern boundary to about 30 km of depth. The study also provided new constraints on the geometry of the subducted slab. We noted a great concentration of shallower seismicity compared to that of the surrounding areas of the Wadati-Benioff zone, at the expected position of the Juan Fernandez Ridge (JFR). Our hypocentres indicate that JFR certainly influences the subduction style along its strike, leading to the formation of a bend in the slab geometry.157 25