We have determined the centroid depths and source mechanisms of 14 earthquakes along spreading centers in the Indian Ocean, Gulf of Aden, and Red Sea. The earthquakes are all characterized by normal faulting on planes dipping at about 45¿ and generally striking parallel to the local trend of the spreading center. For the ridge axis earthquakes in the Indian Ocean, Gulf of Aden, and central Red Sea, seismic moments range from 3 to 9¿1024 dyn cm, source time functions are all of simple form, and centroid depths of events with adequate azimuthal coverage are all very shallow, between 1 and 4 km beneath the seafloor. If the centroid depth typically marks the mean depth of fault slip, then earthquake faulting extended to 2--8 km beneath the seafloor during these earthquakes. The centroid depths for two earthquakes near the mouth of the Gulf of Suez support the view that seismic faulting accompanying continental rifting generally extends to greater depth than does seismic faulting along the axes of oceanic spreading centers. When these findings are combined with our earlier results from the Mid-Atlantic Ridge, the greatest centroid depths of earthquakes with well-constrained source mechanisms tend to shoal with increasing spreading rate. This result supports a general decrease with spreading rate in the maximum thickness of the zone of brittle behavior for slow spreading ridges. ¿ American Geophysical Union 1987