HR: 15:30h
AN: GP53A-06    [Abstracts]
TI: Apparent Density Mapping Using Entropic Regularization
AU: * Barbosa, V C
EM: valcris@on.br
AF: Observatório Nacional (ON), Rua Cristino, 77, São Cristóvão, Rio de Janeiro, RJ 20921-400, Brazil
AU: Silva, J B
EM: joaobcs@oi.com.br
AF: Universidade do Pará (UFPA), Rua Augusto Correa, 1, Belém, PA 66017-900, Brazil
AU: Oliveira, F S
EM: frasol@ufpa.br
AF: Universidade do Pará (UFPA), Rua Augusto Correa, 1, Belém, PA 66017-900, Brazil
AU: Campos Velho, H F
EM: haroldo@lac.inpe.br
AF: Instituto Nacional de Pesquisas Espaciais (INPE-LAC), Av. dos Astronautas,1758, São Jose dos Campo, SP 12227-010, Brazil
AB: We present a new apparent density mapping on the horizontal plane, which combines the minimization of the first-order entropy with the maximization of the zeroth-order entropy of the estimated density contrasts. The interpretation model consists of a grid of vertical, juxtaposed prisms in both horizontal directions. We assume that the top and the bottom of the gravity sources are flat and horizontal and we estimate the prisms density contrasts. The minimization of the first-order entropy favors solutions presenting sharp borders, and the maximization of the zeroth-order entropy prevents the tendency of the source to collapse to a single prism, so a judicious combination of both constraints may lead to solutions characterized by regions with virtually constant estimated density contrasts separated by sharp discontinuities. The method has been applied to synthetic data from simulated intrusive bodies in sediments, presenting flat and horizontal tops. By comparing our results with those obtained with the smoothness constraint, we show that both methods produce good and equivalent locations of the sources' central positions, but the entropic regularization delineates the boundaries of the bodies with greater resolution. Both the proposed and the global smoothness constraints have been applied to real anomalies from the eastern Alps, and from the Matsitama intrusive complex, northeastern Botswana. In the first case, the entropic regularization delineates two sources with horizontal and nearly flat top being consistent with the known geological information. In the second case, both constraints produced virtually the same estimate indicating, in agreement with results of synthetic tests, that the tops of the sources are neither flat nor horizontal.
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly