On midnight of August 17, 1976, a devastating Magnitude 8 earthquake, triggered by the movement of the Cotabato Trench, caused a huge tsunami that hit the island of Mindanao.
The tsunami affected 700 kilometers of coastline bordering the Moro Gulf, affecting coastal areas in the provinces of Maguindanao, Sultan Kudarat, Lanao del Sur, Lanao del Norte, Zamboanga del Sur, Basilan and Sulu, and the cities of Cotabato, Zamboanga and Pagadian. Maguindanao posted the highest number of dead and missing, followed by Lanao del Sur.
https://www.mindanews.com/wp-content/uploads/2019/08/MoroGulf_1976complete.pdf
Related Links:
Babu Minang, survivor of 1976 tsunami: “Nothing was left
The 1976 tsunami: Maguindanao had highest death toll
Moro Gulf Tsunami of 17 August 1976: By Victor L. Badillo and Zinnia C. Astilla
The Earthquake and Tsunami of August 1976 in the Philippines
