The 1975 event near the Hawaii Island coast had magnitude 7.7, with a maximum Mercalli intensity of VIII, and caused a near-field tsunami reaching roughly 40–47 feet, resulting in loss of two lives and millions of dollars in damage. The quake produced subsidence and ground cracking on the Big Island, and the tsunami reached far-field locations, while shoreline changes included notable subsidence. The event is linked to the Hilina Slump source and to earlier seismic activity in the region.
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November 29, 2025 marks the 50th anniversary of the M7.7 earthquake that struck just offshore of the southern coast of Hawaii’s Big Island, generating a deadly tsunami.
quakefeed.substack.com80th Governor George R. Ariyoshi and President Gerald R. Ford declared Hawaii County a major disaster area due to an earthquake-tsunami which struck there at 4:48 a.m., Nov. 29, 1975. Within minutes, a tsunami with 40-foot waves followed the earthquake. Two people were killed and approximately $4.1 million in property damage occurred due to the […]
dod.hawaii.govA magnitude 7.7 (revised 2018) earthquake off the coast of the Island of Hawaii (the “Big Island”) on November 29, 1975, was felt throughout the island, as well as on Lanai, Molokai, and Oahu. The quake caused extensive ground cracking and subsidence; in one area, the coast permanently subsided over 11 feet. The quake triggered a near-field tsunami, with waves up to nearly 26 feet in the area of Halape; far-field tsunami waves were recorded in Alaska, California, Japan, and Samoa.
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