We present a comprehensive study of the seismicity of the Antarctic plate for the period 1925-1980. The total seismic energy released during this period in the interior of the plate, 3.2 × 1022 ergs, is compared to figures for the African plate, of similar kinematics and size, and to the neighboring Nazca plate. We conclude that Antarctic seismicity is comparable to that of other plates, thus refuting the claim that a surrounding ring of spreading ridges hampers transmission of tectonic stress and leaves it stress-free, and clearly showing the importance of ridge-push as a driving mechanism for the plates. In the souteastern Pacific Basin, it is shown that the line of maximum age in the plate, which is the locus of previous positions of the triple junction, is a line of preferential stress release, along with more conventional features, e.g. fracture zones. In the Indian Ocean, we study a 1973 earthquake northeast of Kerguelen (Ms = 5.5): its depth (45 km), tensional mechanism, and low stress suggest that it represents a magmatic process related to the nearby hotspot, and possibly involving the pipeline structure proposed by Morgan.
ASJC Scopus subject areas
- Geochemistry and Petrology
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science