INTRAPLATE SEISMICITY OF THE SOUTHERN PART OF THE PACIFIC PLATE.

A compilation is presented of all the known seismicity of the part of the Pacific plate located south of the equator. This includes historical earthquakes dating back to 1937. In addition to the Gilbert Islands swarm of 1981-1983 60 events at 32 epicenters in the magnitude range 4. 3-6. 9 are identified. The results indicate that the level of seismicity of the southern Pacific plate is comparable to that of other plates, including continent-bearing ones. Most of the seismic activity is concentrated in the youngest parts of the plate, but a few large events are present in Cretaceous lithosphere. With the exception of events from the Gilbert Islands swarm, earthquakes located in lithosphere 35 Ma and older are usually compatible with the release of horizontal compressional stress due to the gravitational process known as ridge push; in younger areas the situation is much less clear-cut. The final geometry of the focal mechanisms is controlled by local tectonics.