The 1946 Aleutian Islands earthquake was an earthquake near the Aleutian Islands on April 1, 1946. It was followed by a Pacific-wide tsunami. The earthquake was a magnitude 8.6 (originally rated 7.8 but later revised), with its epicenter at 52.8°N, 163.5°W, and focal depth of 25 km. It resulted in 165 casualties (159 people on Hawaii and six in Alaska) and over $26 million in damages. Multiple destructive waves at heights ranging from 45 – 130 ft occurred.
The tsunami obliterated the Scotch Cap Lighthouse on Unimak Island, Alaska. among others, and killed all five lighthouse keepers. The wave reached Kauai 4.5 hours after the quake, and Hilo 4.9 hours later. This prompted the creation of the Seismic Sea Wave Warning System, which later became the Pacific Tsunami Warning Center in 1949.
The tsunami was unusually powerful for the size of the earthquake and due to the discrepancy between the size of the tsunami and the relatively low magnitude on the surface wave magnitude scale, it is classified as a tsunami earthquake.