The June 17, 1996 (Mw 7.8) Flores Sea event is one of the largest deep earthquakes, and also produced an energetic aftershock sequence, allowing study of the spatial relationships between moment release, aftershock occurrence, and slab geometry. The locations of the mainshock, rupture sub-events, aftershocks, and background slab seismicity are determined using a relative location algorithm. The event occurred at the edge of a 150 km wide aseismic region that represents a tear in the lowermost part of the Indonesian slab. The aftershocks define a 90 km long region parallel to slab strike. Two other aftershocks locate 10--25 km outside the previously active slab. The mainshock propagated about 75 km eastward along an E-W striking, southward dipping plane, with a rupture velocity of 3.5 km/s. There was a substantial change in focal mechanism during the rupture, with the fault plane strike changing by about 25¿. Overall, the Flores Sea deep earthquake shows numerous large aftershocks, and a moderate rupture velocity (3.5 km/s) and stress drop (~7--20 MPa.)These characteristics are similar to the 1994 Tonga deep earthquake, but different from the 1994 Bolivia event, suggesting they may be typical of large deep earthquakes in colder slabs. Systematic differences in rupture parameters for deep earthquakes in warm and cold slabs suggest that the rupture mechanism is highly sensitive to temperature. ¿ 1998 American Geophysical Union