what kind of mantle activity causes volcanism on hawaii
Hawaii hotspot Wilson proposed that mantle convection produces small, hot buoyant upwellings under the Earth's surface; these thermally active mantle plumes supply magma which in turn sustains long-lasting volcanic activity. This "mid-plate" volcanism builds peaks that rise from relatively featureless sea floor, initially as seamounts and later as fully-fledged volcanic islands. The local tectonic plate (in the case of the Hawaii hotspot, the Pacific Plate) slowly slides over the hotspot, carrying its volcanoes with it without affecting the plume. Over hundreds of thousands of years, the magma supply for the volcano is slowly cut off, eventually going extinct. No longer active enough to overpower erosion, the volcano slowly sinks beneath the waves, becoming a seamount once again. As the cycle continues, a new volcanic center manifests, and a volcanic island arises anew. The process continues until the mantle plume itself collapses.[1]
Mauna Loa Mauna Loa is one of five subaerial volcanoes that make up the island of Hawaiʻi, created by the Hawaii hotspot.[10] The oldest volcano on the island, Kohala, is more than a million years old,[11] and Kīlauea, the youngest, is believed to be between 300,000 and 600,000 years of age.[10] Lōʻihi Seamount on the island's flank is even younger, but has yet to breach the surface.[12] At 1 million to 700,000 years of age,[2] Mauna Loa is the second youngest of the five volcanoes on the island, making it the third youngest volcano in the Hawaiian – Emperor seamount chain, a chain of shield volcanoes and seamounts extending from Hawaii to the Kuril–Kamchatka Trench in Russia.[13]