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Uso De Emanometria Do Gás Radioativo 222Rn Da Série Do 238U, Para Detecção De Fraturas Em Rochas
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 6th International Congress of the Brazilian Geophysical Society, Aug 1999, cp-215-00068
Abstract
In Nuporanga locality (SP) occurred many induced earthquakes along 1970 decade, owing to drilling and<br>exploitation activities of pipe wells that crossed basaltic layers of Parana Basin. Since that, seismographs were<br>installed to detect earthquakes and feasible cause of phenomenon. At this work, the objective of radon (222Rn)<br>gas emanometry was detection and measurement of fractures azimuths near these wells. Emanometry profiles<br>near four wells were made to test the method. In each point of these profiles, were buried accumulation tubes,<br>separated by 5 meters, that accumulated Rn gas exhaled from soil, during 3 days. Using a Lucas alpha<br>scintillation cells, was possible to delineate, surely anomaly regions of Rn gas exhalation, considering counting<br>statistic errors and the noise of measurements systems. The content of U and Th in basaltic layers are<br>negligible and,therefore the emanation rate of Rn from soil should be low. Meanwhile, in some collecting point,<br>the observed value was relativelly high, that allowed to infer an probably fracture alignments in directions NE or<br>NW