The geologically young Samoan Islands are situated in a seismically active area in the Pacific Ocean, at the northern end of the Kermadec-Tonga Trench. The paper discusses two faults not shown on the 1: 100 000 geological maps of the area. One of the faults, trending northwest/southeast, has been postulated as passing through the Afulilo dam site. The other fault trends northeast/southwest, displacing the line of the recent volcanic cones by up to 2.5 km. Any movement along this fault could affect the integrity of the hydroelectric powerhouse and a possible future intake structure.