Results of the magnetotelluric investigations at geophysical observatories in Bulgaria

0494313 - GFÚ 2019 RIV GB eng J - Článek v odborném periodiku
Srebrov, B. - Logvinov, I. M. - Rakhlin, L. - Kováčiková, Světlana
Results of the magnetotelluric investigations at geophysical observatories in Bulgaria.
Geophysical Journal International. Roč. 215, č. 1 (2018), s. 165-180. ISSN 0956-540X. E-ISSN 1365-246X
Institucionální podpora: RVO:67985530
Klíčová slova: structure of the Earth * Europe * magnetotellurics * numerical modelling * electrical properties
Obor OECD: Physical geography
Impakt faktor: 2.777, rok: 2018

We present results of the geoelectric studies in Bulgaria, carried out with the GEOMAG-02 equipment at the geophysical observatories of the Bulgarian Academy of Sciences. Compared with previous long-period electromagnetic investigations carried out with an analogue device by Russian and Bulgarian geophysicists in the 1980s the application of modern equipment and processing methods makes it possible to obtain interpretive options for the periods from a few seconds up to 3 hr and study the geoelectric structure at shallower depths. The recorded data together with the previous long-period data were analysed and the 1-D, 2-D and quasi-3-D inversion have been employed to model the conductivity distribution within the Earth's crust of Bulgaria. Some of the revealed conductivity anomalies seem to spatially coincide with the regional fault zones-Maritsa and Sub-Balkan. Joint interpretation of the 2-D and quasi-3-D inversion results suggests the relation of one of these conductivity anomalies near the PLN observatory to the Maritsa fault zone. The association of some of revealed conductivity anomalies with the fluid transport processes is supported by the fracture-type hydrothermal reservoirs widespread in the studied area south of the Sub-Balkan fault ( and especially south of theMaritsa fault) and by the audiomagnetotelluric case study in the Bourgas geothermal basin in the eastern part of Bulgaria. A comparison of the distribution of conductivity anomalies, determined from the quasi-3-D inversion, and seismicity shows that most of the earthquakes occur outside the high conductivity areas. In seismoactive regions such effect may indicate possible association with metamorphic processes in the crust with the participation of fluids within the fractured media.
Trvalý link: http://hdl.handle.net/11104/0287500