The volcano was formed by subaerial eruptions between 1.54 and 1.28 million years ago.[1] It has been estimated that the volcano was as high as 3,937 feet (1,200 m) above sea level.[2] Activity on Pago Volcano ended with emplacement of trachyte bodies with ages of 1.03 ± 0.01 Ma.[3]
The Pago Volcano caldera was formed 1.27+-0.02 million years ago. The caldera's dimensions are estimated at 5.9 miles (9.5 km) in length and 3 miles (4.8 km) in width.[4] The southeast part of the caldera makes up Pago Pago Harbor, one of the world's largest natural harbors. The northwest rim, Maugaloa Ridge, creates the southern border of the National Park of American Samoa.[5]
^Keating, Barbara H.; Bolton, Barrie R. (2012), Geology and Offshore Mineral Resources of the Central Pacific Basin, Springer Science & Business Media, p. 152, ISBN9781461228967.
^Harris, Ann G. (2004), Tuttle, Esther; Tuttle, Sherwood D. (eds.), Geology of National Parks(PDF) (Sixth ed.), Dubuque, Iowa: Kendall/Hunt Publishing Company, p. 614, ISBN0-7872-9971-5.