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 No longer active enough to overpower erosion, the volcano slowly sinks beneath the waves, becoming a seamount once again.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 Kea Mauna Kea (/ˌmɔːnə ˈkeɪ.ə/ or /ˌmaʊnə ˈkeɪ.ə/, Hawaiian: [ˈmɐwnə ˈkɛjə]), is a dormant volcano on the island of Hawaii. Standing 4,207 m (13,802 ft) above sea level, its peak is the highest point in the state of Hawaii making the island of Hawaii the second highest island in the world. Most of the mountain is underwater; when measured from its oceanic base, Mauna Kea is over 10,000 m (33,000 ft) tall and is the tallest mountain on Earth.[5] Mauna Kea is about a million years old, and has thus passed the most active shield stage of life hundreds of thousands of years ago. In its current post-shield state, its lava is more viscous, resulting in a steeper profile. Late volcanism has also given it a much rougher appearance than its neighboring volcanoes; contributing factors include the construction of cinder cones, the decentralization of its rift zones, the glaciation on its peak, and the weathering effects of the prevailing trade winds. Mauna Kea last erupted 6,000 to 4,000 years ago and is now considered dormant.