Mechanisms and depths of Atlantic transform earthquakes.

We have studied 40 earthquakes on 7 major transforms along the Mid-Atlantic Ridge. The majority show the expected transform-parallel strike-slip motion on steeply dipping fault planes. Some 'anomalous' mechanisms, suggesting either unusually shallow dip or a component of dip-slip motion, occur near ridge-transform intersections. The vertical tectonism suggested by transform morphology may thus be restricted to intersections where thermal contrast across the transform is greatest and stress orientations can be oblique to both ridge and transform.-from Authors