Magnitude 6.3 Earthquake Depth 10 km Strikes Pacific-Antarctic Ridge on 2nd April 2025

It is regarded as the southern section of the East Pacific Rise in some usages, generally south of the Challenger fracture zone which is associated with a triple junction between the Juan Fernández microplate, the Pacific plate and the Antarctic plate. It stretches from there in a general southwesterly direction to the Macquarie Triple Junction south of New Zealand.

The divergence rate between the two plates along the ridge is believed to vary from about 5.4 centimetres per year (2.1 in/year) near 65°S to 7.4 centimetres per year (2.9 in/year) near the Udintsev fracture zone at 55°S. This area of transition in sea floor spreading rate has been mapped by multiple techniques and occurs near the Heirtzler fracture zone.

The ridge is related to the Late Cretaceous breakup of Gondwana. To the southeast the historic Bellingshausen plate separated the Pacific and Antarctic plates between about 84 to 61 million years ago. Until about 33 million years ago, the Proto-Antipodes fracture zone well to the south separated two independent spreading centres, now merged, being the Antarctic–Pacific Ridge and that of the Antarctic–Campbell Plateau.

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