RELATIONSHIP BETWEEN THE DEEP STRUCTURE AND GEODYNAMICS OF THE CARPATHIANS ARC BEND
For long time electromagnetic data supplied a large scale of information regarding the deep structure of the geodynamics of this area. By finding out how is influenced the propagation of the electromagnetic field depending on the various particularities of the deep structure and establishing a relationship between them, we have tried to reveal a relationship between the possible changes in the crust and upper mantle structure, on the hand, and electromagnetic parameter having an invariant character (Bzn) in the absence of the seismic activity, on the other hand. Under these circumstances, we used the data carried out by electromagnetic-multitechniques monitoring at Tulnici and Provita geodynamic observatories, for long periods so that these data may be correlated with significant seismic events (M >4,5) occurred in the active Vrancea zone. In the investigated area, our interest is focused on the Vrancea zone, which is located within the arcuate portion of Eastern Carpathians, because it is particularly a complex seismic-active zone of continental convergence, where more tectonic units are in contact: Intra-Alpine and Moesian subplates, and the East from the East European Plate, considered to be the main seismogenic volume in the area. All the characteristics concerning the structure and the geometry of this slab were assessed mainly through the analysis of 3-D magnetotelluric tomographic imaging and tensor impedance polar diagrams constructed for a large scale of frequencies corresponding to intermediate-depth intervals (70-150 Km). The orientation of the major axes of the diagrams records a counterclockwise rotation with depth, hence suggesting that the slab underwent some torsion.In this paper it is to highlight an up-dated geodynamic model at subcrustal level and an analysis of the electromagnetic monitoring data and the seismic events for the last three years, so that a coherent relationship between these to be emphasized.
geodynamics Vrancea zone electromagnetic Bzn invariant magnetotelluric tomographies
Dumitru Stanica Dragos Armand Stanica
Institute of Geodynamics of the Romanian Academy, Bucharest, Romania
国际会议
The 19th International Workshop on Electromagnetic Induction in the Earth(第十九届国际地球电磁感应学术研讨会)
北京
英文
137-142
2008-10-23（万方平台首次上网日期，不代表论文的发表时间）