Spacial distribution and time variation in seismicity around the Antarctic Plate-Indian Ocean region

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Spacial distribution and time variations in seismicity around the Antarctic Plate-Indian Ocean (0-160°E , 20-80°S ) is evaluated based on the data compiled at the global seismological centers since 1964. Seismicity in the oceanic area of the Antarctic plate, along with ridges/transform faults between the Indian-Australian Plate, represents characteristic features before and after large earthquakes, such as the Balleny Earthquake on March 25, 1998. Seismicity in the aseismic ridges immediately east of the Australia-Antarctic Discordance (AAD) increased the year before occurrence of the Balleny Earthquake. Long period variations in seismicity during more than 30 years imply several characteristic time periods of increase in cumulative seismicity, associated with dynamic distribution of tectonic stress in space and time between adjacent plates. Time variations in seismicity around the Balleny Earthquake region, in particular, drastically changed before and after the main shock in March 1998. The recent distribution of hypocenters in this area appears to extend toward Wilks Land, followed by the excitation of local events beneath the continental ice sheet of Antarctica. Seismic activities of these areas might reflect far-field tectonic stress in the lithosphere around the region.
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