![]() The increase in volume of mantle material at a hotspot causes the Pacific Ocean floor to elevate as the Pacific Plate moves over the Hawaiian Hotspot. Solid materials commonly expand as they heat up. In Hawaii Volcanoes National Park, magma rising in vertical, sheet-like patterns results in fissure eruptions through rift zones out of the flanks of Kilauea and Mauna Loa. ![]() Some of the magma hardens into sheet-like dikes below the surface, or is carried great distances through underground lava tubes before emerging as surface flows. Although summit eruptions occur, more often the magma spreads outward and erupts through long fissures along the flanks of the volcano, known as rift zones. Magma can accumulate in chambers beneath the summit region of a shield volcano. Eventually, the island is totally submerged (Koko Seamount).įeatures at Hawaii’s national parks provide intriguing clues about the way magma flows beneath a volcano and eventually reaches the surface. The island gradually erodes and sinks until all that remains are coral reefs just above sea level (Midway Atoll). After moving over the hotspot, volcanic activity wanes (Maui) and eventually ceases. An island emerges as lava erupts on the seafloor (Loihi) and eventually piles up above sea level (Hawaii). The Hawaiian Islands-The Emperor Seamount Chain develops as volcanoes form above the Hawaiian Hotspot and then ride away on top of the Pacific Plate. Low-lying atolls and submerged volcanoes along the Hawaiian Ridge and Emperor Seamount Chain represent the two last stages caused by erosion and thermal subsidence some distance from the hotspot. Hawaii Volcanoes and Haleakala national parks have features that reflect the second and third stages, respectively, as volcanic islands develop over the hotspot and are then transported away by the moving plate. On the southeast, a still-submerged volcano called Loihi represents the initial stage. The islands, atolls, and seamounts of the Hawaiian Island – Emperor Seamount Chain illustrate the stages of development as the Pacific Plate moves over the Hawaiian Hotspot. Haleakala National Park encompasses the summit area of Haleakala Volcano, which has moved off the hotspot but still has some eruptions. Hawaii Volcanoes National Park lies directly above the Hawaiian Hotspot and includes portions of two very active volcanoes, Kilauea and Mauna Loa. In 1961, that large park was separated into Hawaii Volcanoes National Park on the Big Island of Hawaii, and Haleakala National Park on Maui. In 1916, the same year the National Park Service was formed, Hawaii National Park was established to preserve and showcase the Hawaiian Islands’ volcanic features.
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