Hawaiian Islands

The Hawaiian Islands, once known as the Sandwich Islands, form an archipelago of nineteen islands and atolls, numerous smaller islets, and undersea seamounts trending northwest by southeast in the North Pacific Ocean between latitudes 19° N and 29° N. The archipelago takes its name from the largest island in the group and extends some 1500 miles (2400 km) from the Island of Hawai‘i in the south to northernmost Kure Atoll. The archipelago represents the exposed peaks of a great undersea mountain range known as the Hawaiian-Emperor seamount chain, formed by volcanic activity over a hotspot in the earth's mantle. At about 3,000 km (1,860 miles) from the nearest continent, the Hawaiian Island archipelago is the most isolated grouping of islands on Earth (Macdonald, Abbott, and Peterson, 1984).

Geology

The chain of islands or archipelago formed as the Pacific plate moves slowly northwestward over a hotspot in the earth's crust.

Related Topics:
Archipelago - Hotspot

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Hence the islands in the northwest of the archipelago are older and typically smaller (have been eroding far longer). Because of the composition of the magma in the hotspot, the composition of Hawaiian volcanoes is basaltic. The majority of eruptions in Hawai‘i are Hawaiian-type eruptions because basaltic magma is relatively fluid compared with andesitic eruptions.

Related Topics:
Basalt - Hawaiian-type eruption

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Hawai‘i (the Big Island) is the largest and youngest island in the chain, built from seven different volcanoes. Mauna Kea, comprising over half of the Big Island, is the largest shield volcano on the planet. The measurement from the base locally depressing the sea floor to its peak is abut 17 km (56,000 feet; USGS)

Related Topics:
Mauna Kea - Shield volcano

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See also: List of Hawaii rivers

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