The Samoan islands have been produced by vulcanism, the source of which is the Samoa hotspot which is probably the result of a mantle plume. While all of the islands have volcanic origins, only Savai'i, the western most island in Samoa, is volcanically active with the most recent eruptions in Mt Matavanu (1905–1911), Mata o le Afi (1902) and Mauga Afi (1725). The highest point in Samoa is Mt Silisili, at 1858 m (6,096 ft). The Saleaula lava fields situated on the central north coast of Savai'i are the result of the Mt Matavanu eruptions which left 50 km² (20 sq mi) of solidified lava.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): When was a mantle plume discovered near Magua Alfi?
unanswerable