The Hawaiian are the product of a mantle hot spot in the middle of the Pacific Plate. The hot spot's current activity is underneath the southern end of the island of Hawaii. Once the volcanoes go extinct, the islands continue to erode until slipping below sea level. The Pacific Plate is carrying the length of islands and seamounts to the northwest side as it drifts. A hot spot under the American plate is why Yellowstone National Park has geysers, the hot spot is under the seafloor which is why it produces undersea volcanoes. The Hawaiian Islands feature; Kauai, Oahu, Maui, then Hawaii itself.
Kauai is the oldest of them, having formed around 5 million years ago, with the volcano considered to be extinct and fully in the process of erosion. Oahu is next, its volcanism is known to be inactive. Then Maui with its Haleakala crater that could possibly come to life one more time. And the youngest is Hawaii, with surface lavas that is less than one million years old, although it still has active volcanism. Lava flowing into the ocean is rarely seen but, in Hawaii, it is possible for the general tourist to view this. Hawaii's lava is slow moving and somewhat predictable in its path. The Hawaii Volcanoes National Park sets up a marked trail and signs to guide tourists for the best views of the eruptions. The size of the Hawaiian hot spot is not known, but it presumably is large enough to encompass and feed the currently active volcanoes of the Hawaii Islands. Some scientists have estimated the Hawaiian hot spot to be about 200 miles across, with narrow passageways that feed magma to the individual volcanoes.
Kauai is the oldest of them, having formed around 5 million years ago, with the volcano considered to be extinct and fully in the process of erosion. Oahu is next, its volcanism is known to be inactive. Then Maui with its Haleakala crater that could possibly come to life one more time. And the youngest is Hawaii, with surface lavas that is less than one million years old, although it still has active volcanism. Lava flowing into the ocean is rarely seen but, in Hawaii, it is possible for the general tourist to view this. Hawaii's lava is slow moving and somewhat predictable in its path. The Hawaii Volcanoes National Park sets up a marked trail and signs to guide tourists for the best views of the eruptions. The size of the Hawaiian hot spot is not known, but it presumably is large enough to encompass and feed the currently active volcanoes of the Hawaii Islands. Some scientists have estimated the Hawaiian hot spot to be about 200 miles across, with narrow passageways that feed magma to the individual volcanoes.