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.
Geology of the United States
The State of Hawaii consists of a chain of islands, or archipelago. The archipelago developed as the Pacific plate moved slowly northwestward over a hotspot in the Earth's mantle at a rate of approximately per million years. Thus, the southeast island (Hawaii) is volcanically active whereas the islands on the northwest end of the archipelago are older and typically smaller, due to longer exposure to erosion. The age of the archipelago has been estimated using potassium-argon dating methods. From this study and others, it is estimated that the northwestern most island, the Kure Atoll, is the oldest at approximately 28 million years (Ma); while Hawaii, is approximately 0.4 Ma (400,000 years). The only active volcanism in the last 200 years has been on Hawaii and on the submerged but growing volcano to the extreme southeast, Loihi.