Samoa Hotspot - Vailulu'u

Vailulu'u

In 1975, geophysicist Rockne Johnson discovered the Vailulu'u Seamount, 45 km east of Ta'u island in American Samoa which has since been studied by an international team of scientists. Within the summit crater of Vailulu'u is an active underwater volcanic cone called Nafanua, named after a war goddess in Samoan mythology. The study of Vailulu'u provides scientists with another possible model for hotspots as an alternative to the Hawai'i hotspot model.

An important difference between Vailulu'u and Loihi in Hawai'i, is a total lack of tholeiitic basalt compositions at Vailulu'u although both are located at the easternmost point of their respective island chains.

The northern Tonga Islands (Vava'u and Niuatoputapu) are moving away from Fiji on the Australian plate at rates of about 130 mm/yr and 160 mm/yr, respectively, while Niue and Rarotonga on the Pacific plate are approaching the Australian plate at about 80 mm/yr. This implies that Pacific plate is tearing at the corner of the trench-transform boundary at a rate that is the sum of these two (160 + 80) 240 mm/yr.