ISSN:
1420-9136
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Summary To the residual data ofEnayatollah [11] are fitted sine curves with back-azimuth as the independent variable. The result is a clear regional trend towards apparently earlyP-wave arrivals from the north relative to those from the south at any one station for δ≥55o. Explanations are plausible, but not entirely satisfactory, on the basis of systematic epicentral mislocation, or of lateral inhomogeneity inP-velocity structure of the Fennoscandian crust and/or uppermost mantle. A zone of lateral inhomogeneity deeper in the mantle, for example a dipping 600-km discontinuity, consistent with the residual observations, is more likely than a shallower emplacement considering the physical implications of extending such a structure to underlie all or most of Fennoscandia. More fundamental inhomogeneous velocity structure throughout most or all of the mantle may have to be considered to enable epicentral determination and travel-time prediction within the accuracy that present instruments would theoretically permit.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00875824
