The Hawaiian Islands (Hawaiian: Mokupuni Hawaiʻi) are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some 1,500 miles (2,400 kilometers) from the island of Hawaiʻi in the south to northernmost Kure Atoll. Formerly called the Sandwich Islands, the present name for the archipelago is derived from the name of its largest island, Hawaiʻi. The archipelago sits on the Pacific Plate. The islands are exposed peaks of a great undersea mountain range known as the Hawaiian–Emperor seamount chain, formed by volcanic activity over the Hawaiian hotspot. The islands are about 1,860 miles (3,000 km) from the nearest continent and are part of the Polynesia subregion of Oceania. The U.S. state of Hawaii occupies the archipelago almost in its entirety (including the mostly uninhabited Northwestern Hawaiian Islands), with the sole exception of Midway Atoll (a United States Minor Outlying Island). Hawaii is the only U.S. state that is situated entirely on an archipelago, and the only state not geographically connected with North America. The Northwestern islands (sometimes called the Leeward Islands) and surrounding seas are protected as a national monument and World Heritage Site.
Islands and reefs The Hawaiian Islands have a total land area of 6,423.4 square miles (16,636.5 km2). Except for Midway, which is an unincorporated unorganized territory of the United States, these islands and islets are administered as Hawaii—the 50th state of the United States.
Major islands
The eight major islands of Hawaii (Windward Islands) are listed above. All islands except Kaho'olawe are inhabited.
Minor islands, islets
The state of Hawaii counts 137 "islands" in the Hawaiian Chain. This number includes all minor islands (small islands), islets (even smaller islands) offshore of the major islands (listed above), and individual islets in each atoll. These include:
Kaʻula Kāohikaipu Lehua Mānana Mōkōlea Rock Mokoliʻi Moku Manu Mokuauia Moku o Loʻe Moku Ola Mokuʻumeʻume Molokini Nā Mokulua
Partial islands, atolls, reefs
Partial islands, atolls, reefs—those west of Niʻihau are uninhabited except Midway Atoll—form the Northwestern Hawaiian Islands (Leeward Islands):
Nīhoa (Mokumana) Necker (Mokumanamana) French Frigate Shoals (Kānemilohaʻi) Gardner Pinnacles (Pūhāhonu) Maro Reef (Nalukākala) Laysan (Kauō) Lisianski Island (Papaʻāpoho) Pearl and Hermes Atoll (Holoikauaua) Midway Atoll (Pihemanu) Kure Atoll (Mokupāpapa)
Geology
This chain of islands, or archipelago, developed as the Pacific Plate slowly moved northwestward over a hotspot in the Earth's mantle at a rate of approximately 32 miles (51 km) per million years. Thus, the southeast island is volcanically active, whereas the islands on the northwest end of the archipelago are older and typically smaller, due to longer exposure to erosion. The age of the archipelago has been estimated using potassium-argon dating methods. From this study and others, it is estimated that the northwesternmost island, Kure Atoll, is the oldest at approximately 28 million years (Ma); while the southeasternmost island, Hawaiʻi, is approximately 0.4 Ma (400,000 years). The only active volcanism in the last 200 years has been on the southeastern island, Hawaiʻi, and on the submerged but growing volcano to the extreme southeast, Kamaʻehuakanaloa (formerly Loʻihi). The Hawaiian Volcano Observatory of the USGS documents recent volcanic activity and provides images and interpretations of the volcanism. Kīlauea had been erupting nearly continuously since 1983 when it stopped August 2018. Almost all of the magma of the hotspot has the composition of basalt, and so the Hawaiian volcanoes are composed almost entirely of this igneous rock. There is very little coarser-grained gabbro and diabase. Nephelinite is exposed on the islands but is extremely rare. The majority of eruptions in Hawaiʻi are Hawaiian-type eruptions because basaltic magma is relatively fluid compared with magmas typically involved in more explosive eruptions, such as the andesitic magmas that produce some of the spectacular and dangerous eruptions around the margins of the Pacific basin. Hawaiʻi island (the Big Island) is the biggest and youngest island in the chain, built from five volcanoes. Mauna Loa, taking up over half of the Big Island, is the largest shield volcano on the Earth. The measurement from sea level to summit is more than 2.5 miles (4 km), from sea level to sea floor about 3.1 miles (5 km).
Earthquakes
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![Hawaiian Islands: Hawaiian Islands from space.[11]](https://upload.wikimedia.org/wikipedia/commons/thumb/1/1b/ISS-38_Hawaiian_Island_chain.jpg/1280px-ISS-38_Hawaiian_Island_chain.jpg?utm_source=en.wikipedia.org&utm_campaign=parser&utm_content=thumbnail)


