Hawaii hotspot
Hawaiian volcanoes are characterized by frequent rift eruptions, their large size (thousands of cubic kilometers in volume), and their rough, decentralized shape. Rift zones are a prominent feature on these volcanoes, and account for their seemingly random volcanic structure. The tallest mountain in the Hawaii chain, Mauna Kea, rises above mean sea level. Measured from its base on the seafloor, it is the world's tallest mountain, at ; Mount Everest rises above sea level. Hawaii is surrounded by a myriad of seamounts; however, they were found to be unconnected to the hotspot and its volcanism. Kīlauea has erupted continuously since 1983 through Puʻu ʻŌʻō, a minor volcanic cone, which has become an attraction for volcanologists and tourists alike.
Lōʻihi Seamount
Radiometric dating was used to determine the age of rock samples from Lōʻihi. The Hawaii Center for Volcanology tested samples recovered by various expeditions, notably the 1978 expedition, which provided 17 dredge samples. Most of the samples were found to be of recent origin; the oldest dated rock is around 300,000 years old. Following the 1996 event, some young breccia was also collected. Based on the samples, scientists estimate Lōʻihi is about 400,000 years old. The rock accumulates at an average rate of per year near the base, and near the summit. If the data model from other volcanoes such as Kīlauea holds true for Lōʻihi, 40% of the volcano's mass formed within the last 100,000 years. Assuming a linear growth rate, Lōihi is 250,000 years old. However, as with all hotspot volcanoes, Lōihi's level of activity has increased with time; therefore, it would take at least 400,000 years for such a volcano to reach Lōihi's mass. As Hawaiian volcanoes drift northwest at a rate of about a year, Lōʻihi was southeast of its current position at the time of its initial eruption.