Produção Científica
Artigo em Revista
| Hypocentral relocation using clustering-along-planes constraints: implications for fault geometry Hypocentre location is an ill-posed inverse problem even assuming that the velocity model is known, because different sets of hypocentre locations may satisfy the fitting criterion. We present a regularized hypocentre inversion in which the constraints of spatial proximity of the hypocentres to target planes are used. This constraint introduces the geological bias that earthquakes might occur along fault planes. Here, the target planes may be either (1) planes specified by the interpreter or (2) planes fitting groups of events. We assume also that initial estimates of hypocentres and origin times are available. Then, the initial hypocentre estimates, origin times and target planes are used as input to an inversion problem to relocate the hypocentres so that the maximum-possible clustering of events along the given planes is attained, matching the observed traveltimes. We use L1 norm for data fitting, L2 norm for the plane proximity criterion and a polytope algorithm to minimize the functional. Results from synthetic and real data indicate that the plane proximity constraint allows for hypocentre relocation presenting a high degree of clustering along planes. The real-data example is an intraplate earthquake sequence in NE Brazil. Our methodology defined the geometry and strike of fault segments close to known geology and focal mechanism data. In addition, the new method indicates that the fault is characterized by a splay geometry in its southern end and that more than three fault segments are necessary to explain the hypocentre distribution. |
Artigo em Revista
| Evidences of buried loads in the base of the crust of Borborema Plateau (NE Brazil) from Bouguer admittance estimates In the Borborema Province (BP) e northeastern Brazil e two important Cenozoic events occurred at the surface: the Macau magmatism and the Borborema Plateau epeirogenesis. To obtain appropriated-scale geophysical data to explain the deep origins of these two events, different gravimetric/elevation databases were integrated with new surveys. Bouguer admittance estimates reveal that isostatic condition of the BP, especially in the Borborema Plateau, can be explained using elastic models to the lithosphere only if surface and buried loadings are combined. If the buried load is applied in the base of the crust, the ratio between buried and surface weights is circa 15 for a lithosphere with effective elastic thickness around 15 km and crust thickness around 33 km. From an nterpretative viewpoint of the buried load, it is assumed that the lower crust under the Borborema Plateau might have an anomalous high value of density. Magmatic underplating might explain this fact as well as the observed surface magmatism and epeirogenesis. Crustal thickening of about 4 km under the Borborema Plateau and intracrustal seismic velocity discontinuity with high Vp/Vs ratio are geophysical facts consistent with magmatic underplating. However, the surface magmatism presents low volume and mainly alkaline composition e facts that are not entirely consistent with the hypothesis of magmatic underplating. Regardless the validity of this hypothesis, Cenozoic-to-present events in BP might be somewhat associated with imbalances in lithosphere-asthenospheric mantle and/or crust-lithospheric mantle systems. The existence of free-air anomalies showing no null integral over area and of an expressive positive geoid anomaly are geophysical evidences of these imbalances. Possibly, the Borborema Plateau is still suffering epeirogenesis. Post-depositional deformation found in Barreiras Formation strata, Late Quaternay fault reactivations, and AFT thermochronology analysis suggesting the existence of a cooling stage between 20 and 0 Ma might be geologic evidences of the continued action of peirogenesis until the present. In addition, the relatively high level of the present intraplate seismicity recorded in several regions of the BP is another unequivocal geophysical evidence that the crust of the province is still submitted to accommodation processes. |
Apresentação
| Anisotropic physical modeling Jose Jadsom S. de Figueiredo, Robert Stewart, Joerg Schleicher, Nikolay Dyaur, Bode Omoboya, Robert Wiley and Anoop William. 1º Workshop do INCT-GP (2011) |
Apresentação
| Estimação numérica do moveout para análise de velocidade de migração em super-gathers Momoe Sakamori e Ricardo Biloti. 1º Workshop do INCT-GP (2011) |
Apresentação
| Estimating quality factor from surface seismic data: a comparison of current approaches Bonnie Ives de Castro Nunes, Walter Eugênio de Medeiros, Aderson Farias do Nascimento, José Antonio de Morais Moreira. 1º Workshop do INCT-GP (2011) |
Apresentação
| Scattering-based decomposition of sensitivity kernels for full-waveform inversion Daniel Leal Macedo, Ivan Vasconcelos e Joerg Schleicher. 1º Workshop do INCT-GP (2011) |
Apresentação
| Estereotomografia para estimativa de macro-modelos de velocidades em imageamento sÃsmico: Aplicação em dados reais da Bacia do Jequitinhonha Felipe Antonio Terra, Jessé Carvalho Costa e Amin Bassrei. 1º Workshop do INCT-GP (2011) |
Apresentação
| Migração 3D em profundidade usando aproximação de Padé complexa Carlos A. N. da Costa, Itamara do S. Campos, Jessé C. Costa, Francisco de A. S. Neto, Jörg Schleicher e Amélia Novais. 1º Workshop do INCT-GP (2011) |
Apresentação
| Automatic Picking in the Semblance Domain Lourenildo W. B. Leite and Wildney W. S. Vieira. 1º Workshop do INCT-GP (2011) |
Apresentação
| A comparison of stabilized-least squares imaging conditions for wave-equation migration Bruno D. Amaro, Joerg Schleicher, Amélia Novais e Jessé C. Costa. 1º Workshop do INCT-GP (2011) |
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