Juan Fernández plate

The Juan Fernández microplate was first discovered in 1972 via seismicity charts, which showed semi-circular patterns at the Pacific-Nazca-Antarctic triple junction. This implied that shear zone was present that were inconsistent with existing plate theories in the area. The microplate, as it is known today, was first mapped and named in 1983, during a Sea Beam survey that specifically mapped the East Pacific Rise between the Easter and Juan Fernández microplates. near the Juan Fernández microplate. The East ridge outer pseudofault (EOPF), West ridge inner pseudofault (EIPF), West ridge inner pseudofault (WIPF) and ages of sea floor spreading in millions of years (Ma) before present are labelled. == Morphology and geological history ==

This microplate is estimated to have formed approximately 3–4 ago. It contains compressional ridges. The past 1 Ma has not seen any significant change in plate rotation and growth rate since. == Rotation ==

Since the earliest surveys of the area, theories about the movement of the Juan Fernández microplate have evolved to include compression of the plate through rotational movement and also shear zones between two major plates and the Juan Fernández microplate driving this clockwise rotational movement. The Pacific plate is estimated to have a spreading rate anywhere between in relation to the Juan Fernández microplate. Different sources give slightly different vectors with a recent source having relative to the Nazca plate (which is actually moving towards South America), the north-east portion of the Juan Fernández microplate colliding with the Nazca plate at . Approximately 2.5 Ma ago the Juan Fernández microplate began decoupling from the Pacific plate and coupling with the Antarctic plate. The latter severely braked the rotational movement of the microplate. Presently, the Nazca and Antarctic plates, are the plates that share the current shear zones with transform faulting between them and the Juan Fernández plate. The Nazca plate shears to the east while the Antarctic plate shears relatively to the west, and this continues to drive the rotation of the microplate clockwise as well as consequential compression however at a much slower rate. Compression has been observed on the Juan Fernández microplate at the Pacific-Nazca-Juan Fernández triple junction and the Nazca-Antarctic-Juan Fernández triple junction, due to the slightly irregular shape of the plate which does not rotate perfectly about its center. == Possible future fates ==

Some researchers claim that as the triple junction that the Juan Fernández microplate shares with the Pacific plate and the Antarctic plate shifts southwest, the plate will continue to have unimpeded clockwise rotational movement for the foreseeable future. Other researchers propose that due to the extent of compression between the Juan Fernández microplate and the Antarctic plate, the microplate will accrete onto the Antarctic plate within the next million years and simply extend the triple junction between the Pacific, Antarctic, and Nazca plate to the current location of the Pacific-Nazca-Juan Fernández triple junction. Tsunami risk The large 9 October 2014 seismic doublet earthquake within the microplate, raised the potential for significant tsunami generation from thrust tectonics that had not been previously recognised. These paired earthquakes had magnitudes of and and produced at Easter Island away a tsunami. == References ==