3D electrical imaging of near-surface targets

VICTORIA BONGIOVANNI; NÉSTOR BONOMO; MATÍAS DE LA VEGA; MARTINO, LUIS; ANA OSELLA

Barcelona, España

Workshop; 18th International workshop on electromagnetic induction in the Earth; 2006

International Association of Geomagnetism and Aeronomy (IAGA)

We present the results from a geophysical prospection at a historical Jesuit Mission, located in San Ignacio Misiones, Argentina-, which was declared World Monument some years ago. We studied different sectors looking for buried structures; the total area under study covered 36 ha, we will show in this work the results obtained in a sector which at present is at risk of being damaged by a wrong management of the historical resource. In order to optimize the data acquisition and the preliminary in-situ analysis of the results, we first performed an electromagnetic survey using a multifrequency electromagnetic induction device (GEM-2) to have a first insight into the near surface electrical distribution. From 2D and 3D visualization of data, different targets were identified as possible historical structures. Around these anomalous zones, we performed different dipole-dipole profiles, forming high resolution grids for later 3D inversions. Contour maps at constant electrode spacing as well as 3D visualization of data allowed an accurate prediction of the location of the anomalies. Further inversion of the electric and electromagnetic data completed the characterization of the anomalies.