Which island experienced the 1975 Kalapana earthquake and tsunami?

The 1975 Kalapana earthquake and tsunami occurred on the Big Island, officially called Hawaiʻi Island.

The earthquake struck on November 29, 1975, along the southern coast of Hawaiʻi Island. Kalapana, the community that gives the event its common name, lies on the island’s southeastern side near Kīlauea. The earthquake was associated with movement of the Hilina Slump, a large unstable submarine flank of the volcano, and it triggered a powerful local tsunami.

The tsunami reached roughly 14.3 meters, or about 47 feet, in places. At Halapē, two people died and many others were injured. Coastal land also subsided permanently, leaving some areas flooded or altered. The shock had a moment magnitude of about 7.7 and briefly accompanied volcanic activity at Kīlauea.

“Big Island” is the familiar nickname, not the island’s formal name. That distinction causes occasional confusion because Hawaiʻi is both the name of the state and the largest island. The event was not centered on Kauaʻi, Oʻahu, or Maui, even though the earthquake and tsunami were detected across the wider Hawaiian Islands.