Comprehensive sonar imaging of the Easter microplate

Recent GLORIA and SeaMARC II sidescan sonar surveys have imaged virtually the whole of the Easter microplate, and revealed unprecedented detail and complexity in its tectonic fabric and history. There is clear evidence of rapid microplate rotation, of rapidly evolving plate boundaries and of complex deformation near the northern and southern microplate boundaries

Plate boundary reorganization at a large-offset, rapidly propagating rift

THE existence of rapidly spinning microplates along the southern East Pacific Rise has been documented by geophysical swath-mapping surveys1–6, and their evolution has been successfully described by an edge-driven kinematic model7. But the mechanism by which such microplates originate remains unknown. Proposed mechanisms1–10 have generally involved rift propagation11, possibly driven by hotspots or changes in direction of sea-floor spreading. Here we present geophysical data collected over the Earth's fastest spreading centre, the Pacific–Nazca ridge between the Easter and Juan Fernandez microplates (Fig. 1), which reveal a large-offset propagating rift presently reorganizing the plate boundary geometry. A recent episode of rapid 'duelling' propagation of the historically failing spreading centre in this system has created a 120 120 km overlap zone between dual active spreading centres, which may be the initial stage of formation of a new microplate