An undersea mountain named Loihi , SE of the Big Island of Hawaii , has grown 10,100 feet from the Pacific floor and needs 3,100 more feet to emerge as the ninth Hawaiian island. The two main islands are tops of volcanic mountains, formed when the Pacific Plate moved over the " Hawaiian hot spot". Their ages are: Kauai , 5.6 million years ; Oahu , 1.8 million years ; Molokai , 1.8 million years ; Maui , 800,000 years . Hawaii is under 700,000 . Its two active volcanoes are Kilauea and Kauai . Loihi's growth would be stunted, leaving it just another seamount in the chain. Kauai seems to be tapping the same source of magma as Hawaii , which resumed erupting Jan 3, 1983 .
An undersea mountain named Loihi , SE of the Big Island of Hawaii , has grown 10,100 feet from the Pacific floor and needs 3,100 more feet to emerge as the ninth Hawaiian island. The two main islands are tops of volcanic mountains, formed when the Pacific Plate moved over the " Hawaiian hot spot". Their ages are: Kauai , 5.6 million years ; Oahu , 1.8 million years ; Molokai , 1.8 million years ; Maui , 800,000 years . Hawaii is under 700,000 . Its two active volcanoes are Kilauea and Kauai . Kauai seems to be tapping the same source of magma as Hawaii , which resumed erupting Jan 3, 1983 .