Physical properties of the crust and upper mantle in Eurasia through the analysis of waveforms from the Soviet analog seismic network

Seismic networks in the Commonwealth of Independent States (CIS) consist of more than a hundred broadband analog stations and have been in operation for more than 30 years. The longevity of the network, the number and distribution of stations, and the large number of earthquakes recorded has made the seismic data collected by the networks a valuable source of information about the structure of the Earth. The analog recording format and a lack of access to adequate computing facilities has resulted in most of these data undergoing only rudimentary analysis in the past. For this thesis I have collected and digitized several thousands analog records from the archives of more than 30 stations. I found that the quality of the digitized seismograms from the CIS analog stations is good enough to be useful in such types of analysis as the receiver functions, SKS splitting and SS-S differential travel times analysis. Studies of SKS phases recorded by stations in Eastern Europe suggest the existence of a present or recent large-scale mantle flow in central and eastern Europe, parallel to the Alpine belt, which is consistent with the hypothesis of flow proposed previously for the mantle beneath Western Europe. Application of SKS technique to the data recorded in the Altai and Sayan mountains of Central Asia show strain in the mantle beneath the Altai-Sayan region is similar, both in style and scale, to strain in the crust. The receiver functions technique was used to investigate the uppermost layers in the Khibina plutonic region of northern Russia. The results suggest that short (50 km) wavelength lateral variations in the depth of crust-mantle transition persist in this region, despite the cessation of rifting activity in the Kola peninsula in Devonian times. Finally, mapping the upper mantle velocity structure of the Tibetan Plateau and its surroundings with SS-S travel time residuals suggest that while the lithospere beneath southern Tibet is thickened by the India- Eurasian collision, the lithospere beneath the northern Tibet seems normal, not thinned.