Possible nature of seismic activity of Cisdobrogea sag and North Dobrogea depths
© V.I. Starostenko, T.K. Burakhovich, A.N. Kushnir, O.V. Legostayeva, T.A. Tsvetkova, E.M. Sheremet, L.A. Shumlyanskiy
PeriDobruzha depression and its surrounding belong to border zone of the mantle under the EEP, distinguished by the changes
of zero isoline of velocity discrepancies with the depth within the limits of the upper mantle and its transition zone according to the data
of 3D P-velocity model. The system of inclined layers corresponds to mantle border zone. Special features of mantle velocity structure
under PeriDobruzha depression and its surrounding made possible to partition mantle prerequisites of seismicity of the area under
consideration related to manifestation of mantle plume in the lower and medium mantle. Three-dimensional deep geo-electric model
constructed according to the results of modern studies by MTS and MVP methods reflects heterogeneous distribution of present
electric resistance in the depth of the region. Extended for hundreds of kilometers conductors are confined to deep conducting
faults of different rank and their intersections. High-conductivity layer of complicated configuration is distinguished at the southern
flank of the PeriDobruzha depression and occurs at the depths corresponding to lower crust and upper parts of the upper mantle.
The source of the earthquakes as well as the anomalies of high electro-conductivity are mainly corresponding to occurrence of
active deep tectonic faults and connection zones of geological structures of different ages. Within the interval of 28-30 eastern
longitude - 45-46 northern latitude spatial disposition of electric conductivity anomalies comply with the area of manifestation
of deep mantle fluids corresponding to mantle plume.
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