The section of the Southwest Indian Ocean Ridge west of the Prince Edward Fracture zone has a large ridge axis offset and a complicated ridge-transform morphology. We have determined the source mechanisms of transform earthquakes along this portion of the ridge from an inversion of long-period P and SH waveforms. The seismicity is characterized by anomalous faulting mechanisms, source complexity and an unexpectedly large seismic moment release. Several earthquakes with dip-slip components of faulting have been recognized on the central section of the Andrew Bain and 32¿ E transforms suggesting geometrical complexity along the transform. This region has experienced a Mw=8.0 transform earthquake in 1942, yet we observe a seismic slip rate durng the last 20 years that is still comparable to the predicted spreading rate (1.6 cm/yr). The calculated slip rate over a period of 60 years is three times greater than the expected rate of spreading.