Datensatz

Zusammenfassung

Beside plate tectonics, isostatic rebound may be a main contributor in the seismogenic process in Fennoscandia. Extensional horizontal strain, presumably related to land uplift, calculated from mathematical modeling, geodetic data and curvature of uplift, show higher values than compressional horizontal strain, related to ridge push, estimated from sedimentary deformation in the basins surrounding the shield. The location of the current seismicity of central and northern Fennoscandia and the sites of large boulder caves near the Bothnian coast of central Sweden, show high correlation with the maximum curvature of uplift at present and late-glacial time, respectively; the caves may have been created by large earthquakes at the last phase of deglaciation. Large faults in northern Fennoscandia probably also have seismogenic origin dating to the late-glacial period. Differential strain along the Swedish coast of the Gulf of Bothnia, caused by a larger rate of uplift under the Gulf than of the adjacent land, is another seismogenic factor related to rebound. The temporal correlation between the seismicities of the Fennoscandian and the eastern Canadian shields on one hand and segments of the North Atlantic Ridge on the other, gives support to the idea of stress propagation under the Atlantic. -from Author