The travel time of P seismic waves in Europe and Western Russia

Abstract

Over 4000 arrival times at WWSSN stations in Europe from earthquakes in the Eastern Mediterranean and from presumed Russian nuclear explosions are used to define first arrival travel-time curves for the region. Travel times within Europe show no broad regional variation and are considerably slower than those predicted by published velocity models for Fennoscandia and the Russian Platforms. The travel times from the Russian explosions differ only slightly from the European ones and it is concluded that the transition to a region of higher average velocity occurs far enough east for most of the data in this study to be representative of the lower, 'European', velocity structure.

Upper mantle heterogeneities beneath Central Europe

“…Similar remarks apply to the results of Romanowicz (1980) as her upper layer has a thickness of 250km and a much coarser grid structure is used. Finally, England, Kennett & Worthington (1978) and England, Worthington & King (1977) report rather anomalous structures in the depth interval 300-5OOkm beneath southern and central Europe when compared to similar upper mantle velocity distributions for Western Russia and the North Atlantic and Arctic Ocean.…”

Lateral variation in the structure of the upper mantle beneath Eurasia

“…P. C. England, M. H. Worthington and D. W. King The 0.2-km s-l difference in the models over the upper 200-km results from the difference in the stripping models used. The European stripping model is consistent with the first arrival travel times of England & Worthington (1976), while the Russian data are stripped using Der & Landisman's (1972) model SCAN. It should be noted that these stripping models are not chosen arbitrarily, but conform to the available data at shallow depths in the two regions considered.…”

“…In Fig. 5, the corrected EKA slowness data are plotted directly as gradients ('slope lines') on an associated T-A curve, although it should be noted that the first arrival times have been constrained by the European first arrival travel-time curve derived by England & Worthington (1976) from a JED analysis of over 4000 different source-receiver paths. Superimposed on the EKA data in Fig.…”