Possible deep lithospheric roots beneath South-Eastern Carpathians back-arc region

Neagoe, C. and Popa, M. and Diaconescu, M. and Radulian, M. (2010) Possible deep lithospheric roots beneath South-Eastern Carpathians back-arc region. Acta Geodaetica et Geophysica Hungarica, 45 (3). pp. 340-355. ISSN 1217-8977

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Abstract

The Vrancea seismic region represents a unique case of well-defined and intense intermediate-depth earthquake activity as a consequence of specific geodynamic processes at the continental contact between East-European, Moesian and Intra-Alpine plates. Apart the subcrustal earthquakes generated in the Vrancea slab, the analysis of seismicity puts into evidence two other clusters of subcrustal earthquakes (h > 50 km) toward the back-arc side of the SE Carpathians bend, one to the west (Sinaia), the other to the north-west (Bra¸sov Depression) relative to the Vrancea seismic source. The hypocenters lay down between 50 to 105 km in Sinaia and between 50 and 136 km in Bra¸sov Depression. The rate of seismic energy release is much lower (Mw ≤ 3.7 in Sinaia and Mw ≤ 3.1 in Bra¸sov Depression) than for Vrancea activity. The seismicity pattern in the SE Carpathians back-arc region upper mantle correlates well with the high-velocity structures depicted by seismic tomography investigations suggesting possible remnant deep lithospheric roots apart from the narrow well-defined slab generating Vrancea major earthquakes. The results outline significant lateral heterogeneities in the mantle and provide new data for incorporating seismological, geotectonic and volcanological data in a unified modeling of the complex processes taking place in the study region.

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