Integração de dados Geológicos, Sensoriamento Remoto e Geofísico Eletromagnético em investigação de sismogenia induzida nas adjacências do Açude Castanhão – CE

Abstract

This work performed in the city of New Jaguaribara at Castanhão dyke, was motivated by the observation through seismographs of several earthquakes of low magnitude generated since the construction of the dyke in the mentioned area. The objective of this work was to investigate three areas with large concentrations of epicenters near the Castanhão dyke. The investigation was executed using: remote sensing, geological mapping and applied geophysics. Images of Landsat7 and SRTM were used for a digital processing and extraction of structural lineaments both in manual and automated mode, which highlighted a new structure called Michel Arthaud fault, oriented SE - NW. During the geological mapping were realized description of outcrops, structural measures, photographic records and collecting of rock samples. The geophysical method used in this study was the Time Domain Electromagnetic (TDEM) method which was performed in three areas with the highest concentration of epicenters. The profiles were spaced 50 meters for the profiles of Curupatí (New Jaguaribara) and Alagamar (Jaguaretama), and 100 meters for New Jaguaribara. For the data processing the software’s Envi 4.5, Arcgis 9.3 and Geomatics 2012 were used, for geophysical data processing was used IX1D Software. The results and conclusions were the various processing of satellite images, and through them, several structures have been observed. In the pseudo-sections of apparent resistivity, we can observe a great influence of conductive zones associating the seismic events with the infiltration of fluids in the rock fractures. We can conclude that the earthquakes occurred in the Castanhão area may be associated to the water filling in the fractures. And also due to the reactivation of faults, where there is a strong alignment of the epicenters of the main geological structures identified by satellite images and field data.