Banca de QUALIFICAÇÃO: HUGO ESTEBAN POVEDA NUÑEZ

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : HUGO ESTEBAN POVEDA NUÑEZ
DATA : 25/05/2016
HORA: 15:00
LOCAL: Auditório do DGef
TÍTULO:

Upper and middle crustal velocity structure of the northwestern Andean region inferred from ambient noise tomography

PALAVRAS-CHAVES:

 Interferometry, ambient noise, tomography, dispersion curves.

PÁGINAS: 20
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

Group- and phase-velocity maps of the fundamental-mode of Rayleigh waves for the northwestern most corner of South America are developed. The new maps have been developed in the 6 - 38 s period range from the cross-correlation of seismic ambient noise recorded at 53 broadband stations operated by the Colombian Geological Survey, providing a good coverage of the Andean region. Over 1300 empirical Green’s functions with raypaths between 100 and 1300 km were extracted from inter-station cross-correlations, obtained after normalizing the ambient seismic noise recordings in both the frequency and time domains and stacking up to 32 months (2012-2015) of normalized data. The group-velocity curves from the various paths were then inverted to produce maps in a 0.5˚ x 0.5˚ grid using a non-linear, iterative, 2-D tomographic scheme that updates the propagation paths using the Fast Marching Method. Dispersion maps show good correlation with surface geology down to 20 s. Low-velocity anomalies correlate with Cenozoic sedimentary rocks and Quaternary deposits around the Caribbean and Pacific coast and, in the Eastern range, with de Cenozoic and Cretaceous sedimentary cover. High velocity anomalies along the Central range and the Sierra Nevada of Santa Marta seem to be related to igneous metamorphic Jurassic and Cretaceous structures and with Precambrian and Paleozoic basement. We also inverted group- and phase-velocity measurements simultaneously for a 1-D shear wave velocity structure at each grid point and generate S-wave velocity maps at different depths. The models show a thick sedimentary cover around of ~7 km in the Caribbean region, the Magdalena Valley and the Cordillera Oriental. Also we estimate a crustal thickness on the Pacific and Caribbean region less than ~30 km which correlates with previous studies. 

 

 

MEMBROS DA BANCA:
Interno - 1451214 - ADERSON FARIAS DO NASCIMENTO
Interno - 1315614 - DAVID LOPES DE CASTRO
Presidente - 1863578 - JORDI JULIA CASAS
Interno - 349684 - WALTER EUGENIO DE MEDEIROS