Southeast Indian Ridge
The Southeast Indian Ridge (SEIR) is a mid-ocean ridge in the southern Indian Ocean. A divergent tectonic plate boundary stretching almost 6,000 km (3,700 mi) between the Rodrigues Triple Junction (25°S 70°E / 25°S 70°E) in the Indian Ocean and the Macquarie Triple Junction (63°S 165°E / 63°S 165°E) in the Pacific Ocean, the SEIR forms the plate boundary between the Australian and Antarctic plates since the Oligocene (anomaly 13).
The SEIR is the spreading centre closest to the Kerguelen and Amsterdam–Saint-Paul hotspot. The SEIR has an intermediate full spreading rate of 65 mm/yr, and, because Antarctica is virtually stationary, this results in a northward ridge migration of half that rate. Spreading rates along the SEIR varies from 69 mm/yr near 88°E to 75 mm/yr near 120°E.
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