engleski

Lithospheric Structure Beneath Coastal and Continental Croatia Determined from Broadband Teleseismic Waveform Modeling

plicated regions in the Mediterranean. Most seismicity along the Adriatic coast is caused by the interaction of Adria with Dinarides, which sit on the Eurasian plate. Although this general scheme is not disputable, there are open questions regarding the nature of this interaction and the structure of the lithosphere in the Circum-Adriatic region. Seismicity of the continental part of Croatia is less intense: strong events there are relatively rare, but can reach magnitudes exceeding 6, which is typical of intraplate seismicity. Although there were a number of seismic exploration studies, broadband teleseismic data have not yet been used to increase constraints on shallow and deep structure of the area. In the last decade Croatian seismological network has been expanded and modernized, and currently there are 13 digital broadband stations in operation. Using the high-quality seismograms that have been accumulated over the last decade we have computed and analyzed receiver functions for a number of Croatian seismological stations, which helped us gain the first comprehensive insight into the structure of lithosphere beneath Croatia. Most of the stations are located along the coast of the Adriatic Sea and only one station is located deeper inland. Unprocessed data for receiver functions analysis consists of three-component broadband seismograms for selected earthquakes with good signal to noise ratio and epicentral distances between 60° and 90°, mainly confined in the western part of the Pacific Rim, from the Kuril Islands in the north to the Indonesia in the south. To determine lithospheric structure and Moho depth from receiver functions, we used several methods and introduced various improvements in data analysis. We have constrained our velocity/thickness grid search to four layers in the crust using both empirical and best-fit values for Vp/Vs ratio. The values we found for the depth of Moho range from about 30 km for one inland station and exceed 40 km for some stations along the Adriatic coast. We compared our results with Moho maps inferred from interpolated reflection and refraction profiles and found that the agreement is good only for some areas. The interpretation of the 1D profiles that we derived is work in progress. These structural models will also be used to elucidate source mechanisms of both tectonic and volcanic earthquakes that occur in this part of the world.

Listosphere; Croatia

nije evidentirano