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Hawaiian Islands

The Hawaiian Islands are an archipelago of numerous islands and atolls trending northwest by southeast in the North Pacific Ocean between latitudes 19° N and 29° N. The archipelago takes as its name that of the largest island in the group. It extends some 1500 miles from northernmost Kure Atoll to the Island of Hawai'i in the south and represents the exposed peaks of a great undersea mountain range, formed by volcanic activity over a hotspot in the earth's mantle. These islands are part of the State of Hawaii.

Table of contents
1 Islands and reefs of the Hawaiian archipelago
2 Geology
3 Climate
4 Tsunamis

Islands and reefs of the Hawaiian archipelago

NASA satellite photograph of the Hawaiian islands of
O'ahu, Moloka'i, Lana'i, Kaho'olawe, and Maui
(Click )

A total of 19 islands and atolls comprise the Hawaiian Islands, with a total land area of 16,636 km2 (6,423.4 square miles). The main Hawaiian islands (all inhabited except for Kaho'olawe) are, listed here from south to north:

Smaller islands, atolls, and reefs (beyond Ni'ihau and all uninhabited); called the Northwestern Hawaiian Islands: Except for Midway which is an unincorporated territory of the United States, these islands are administered as the State of Hawaii, the 50th of the United States of America.


The chain of islands or archipelago formed as the Pacific plate moves slowly northwestward over a hot spot in the earth's crust. Hence the islands in the northwest of the archipelago are older and typically smaller (have been eroding far longer).

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 considered by some to be the highest mountain on the earth, the measurement from its base localling depressing the sea floor to its peak being 56,000 feet (17 km; USGS)


The islands receive most rainfall from the Northeast Trades on their north and east flanks (called the windward side) as a result of orographic precipitation. Coastal areas in general and especially the south and west flanks or leeward sides, tend to be drier. Because of the frequent build-up of Tradewind clouds and potential showers, most tourist areas have been built on the leeward coasts of the islands.


The hurricane season in the Hawaiian Islands is roughly from July through September, when hurricanes and tropical storms are most probable in the North Pacific. These storms tend to originate off the coast of Mexico or Baja California and track west or northwest towards the islands. Hawai'i is protected by the vastness of the Pacific (i.e. the improbability of a direct hit); as storms cross the Pacific they tend to lose strength if they bear northward and encounter cooler water. It is thought that the topography of the highest islands (Haleakala on Maui, Mauna Kea and Mauna Loa on the Big Island) may protect these islands, and certainly Kaua'i has been hit more often in the last 50 years than the others.


The Hawaiian islands can be affected by tsunamis, great waves that strike the shore typically but not exclusively from the north. Tsunamis are movements of the surface layer of the ocean most often caused by earthquakes somewhere in the Pacific. The city of Hilo on the Big Island has historically been most impacted by tsunamis, where the inrushing water is accentuated by the shape of the bay in front of the town.