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The Hawaiian Islands are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaiʻi in the south to northernmost Kure Atoll. Formerly called the Sandwich Islands by Europeans, the present name for the archipelago is derived from the name of its largest island, Hawaiʻi.
In marine geology, a guyot, also called a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than 200 m (660 ft) below the surface of the sea. The diameters of these flat summits can exceed 10 km (6 mi). Guyots are most commonly found in the Pacific Ocean, but they have been identified in all the oceans except the Arctic Ocean. They are analogous to tables on land.
Kure Atoll or Ocean Island is an atoll in the Pacific Ocean 48 nautical miles west-northwest of Midway Atoll in the Northwestern Hawaiian Islands at 28°25′N178°20′W. A coral ring 6 miles (9.7 km) across encloses a lagoon several meters deep. The atoll's largest island is called Green Island, and is a habitat for hundreds of thousands of seabirds in the present day and wildlife staff. A short, unused, and unmaintained runway and a portion of one building, both from a former United States Coast Guard LORAN station, are located on the island. Politically, it is part of Hawaii, though the nearest island is Midway, which is a separate unorganized territory. Kure Atoll, in addition to being the nesting grounds for tens of thousands of seabirds, has recorded several vagrant terrestrial birds, including snow bunting, eyebrowed thrush, brambling, olive-backed pipit, black kite, Steller's sea eagle and Chinese sparrowhawk. It is currently managed as a Wildlife Bird Sanctuary by the State of Hawaii's Department of Land and Natural Resource–Division of Forestry and Wildlife as one of the co-trustees of Papahānaumokuākea Marine National Monument with support from the Kure Atoll Conservancy. Kure is one of the most westernmost islands of the Northwestern Hawaiian Islands.
The Northwestern Hawaiian Islands also known as the Leeward Hawaiian Islands, are a series of islands and atolls located northwest of Kauai and Niʻihau in the Hawaiian island chain. Politically, these islands are part of Honolulu County in the U.S. state of Hawaii, with the exception of Midway Atoll. Midway Atoll is a territory distinct from the State of Hawaii, and is classified as one of the United States Minor Outlying Islands. The United States Census Bureau designates this area, excluding Midway Atoll, as Census Tract 114.98 of Honolulu County. The total land area of these islands is 3.1075 square miles. With the exception of Nihoa, all these islands lie north of the Tropic of Cancer, making them the only islands in Hawaii situated outside the tropics.
Maro Reef is a largely submerged coral atoll located in the Northwestern Hawaiian Islands. It was discovered in 1820 by Captain Joseph Allen of the ship Maro, after whose ship the reef was named. With a total area of 747 square miles (1,935 km2), it is the largest coral reef in the Northwestern Hawaiian Islands. It contains 37 species of stony coral. Unlike most atolls, the coral extends out from the center like spokes on a wheel. Located about 850 miles northwest of Honolulu, Hawaii, Maro Reef contains about 1 acre (4,000 m2) of dry land which itself can be submerged depending on the tides. Some scientists believe that it "may be on the verge of drowning" because the reefs are detached and are vulnerable to strong storm waves.
The Hawaiian–Emperor seamount chain is a mostly undersea mountain range in the Pacific Ocean that reaches above sea level in Hawaii. It is composed of the Hawaiian ridge, consisting of the islands of the Hawaiian chain northwest to Kure Atoll, and the Emperor Seamounts: together they form a vast underwater mountain region of islands and intervening seamounts, atolls, shallows, banks and reefs along a line trending southeast to northwest beneath the northern Pacific Ocean. The seamount chain, containing over 80 identified undersea volcanoes, stretches about 6,200 km (3,900 mi) from the Aleutian Trench off the coast of the Kamchatka peninsula in the far northwest Pacific to the Kamaʻehuakanaloa Seamount, the youngest volcano in the chain, which lies about 35 kilometres (22 mi) southeast of the Island of Hawaiʻi.
The evolution of Hawaiian volcanoes occurs in several stages of growth and decline. The fifteen volcanoes that make up the eight principal islands of Hawaii are the youngest in a chain of more than 129 volcanoes that stretch 5,800 kilometers (3,600 mi) across the North Pacific Ocean, called the Hawaiian–Emperor seamount chain. Hawaiʻi's volcanoes rise an average of 4,600 meters (15,000 ft) to reach sea level from their base. The largest, Mauna Loa, is 4,169 meters (13,678 ft) high. As shield volcanoes, they are built by accumulated lava flows, growing a few meters or feet at a time to form a broad and gently sloping shape.
Meiji Seamount, named after Emperor Meiji, the 122nd Emperor of Japan, is the oldest seamount in the Hawaiian-Emperor seamount chain, with an estimated age of 82 million years. It lies at the northernmost end of the chain, lies off the coast of the Kamchatka Peninsula, and is perched at the outer slope of the Kuril–Kamchatka Trench. Like the rest of the Emperor seamounts, it was formed by the Hawaii hotspot volcanism, grew to become an island, and has since subsided to below sea level, all while being carried first north and now northwest by the motion of the Pacific Plate. Meiji Seamount is thus an example of a particular type of seamount known as a guyot, and some publications refer to it as Meiji Guyot.
The Hawaiʻi hotspot is a volcanic hotspot located near the namesake Hawaiian Islands, in the northern Pacific Ocean. One of the best known and intensively studied hotspots in the world, the Hawaii plume is responsible for the creation of the Hawaiian–Emperor seamount chain, a 6,200-kilometer (3,900 mi) mostly undersea volcanic mountain range. Four of these volcanoes are active, two are dormant; more than 123 are extinct, most now preserved as atolls or seamounts. The chain extends from south of the island of Hawaiʻi to the edge of the Aleutian Trench, near the eastern coast of Russia.
Detroit Seamount, which was formed around 76 million years ago, is one of the oldest seamounts of the Hawaiian-Emperor seamount chain. It lies near the northernmost end of the chain and is south of Aleutian Islands, at 51°28.80′N167°36′E
The Osbourn Seamount is a seamount in the south-west Pacific Ocean. It is the westernmost and oldest unsubducted seamount of the Louisville Ridge, with an estimated age of 78.8 ± 1.3 Ma. Like other seamounts comprising the Louisville Ridge, it was formed by the Louisville hotspot which is currently located 4,300 km (2,700 mi) away near the Pacific-Antarctic Ridge.
Daikakuji Seamount is a seamount and the southwesternmost volcanic feature in the Hawaiian Emperor chain bend area.
Koko Guyot is a 48.1-million-year-old guyot, a type of underwater volcano with a flat top, which lies near the southern end of the Emperor seamounts, about 200 km (124 mi) north of the "bend" in the volcanic Hawaiian-Emperor seamount chain. Pillow lava has been sampled on the north west flank of Koko Seamount, and the oldest dated lava is 40 million years old. Seismic studies indicate that it is built on a 9 km (6 mi) thick portion of the Pacific Plate. The oldest rock from the north side of Koko Seamount is dated at 52.6 and the south side of Koko at 50.4 million years ago. To the southeast of the bend is Kimmei Seamount at 47.9 million years ago and southeast of it, Daikakuji at 46.7.
Nintoku Seamount or Nintoku Guyot is a seamount and guyot in the Hawaiian-Emperor seamount chain. It is a large, irregularly shaped volcano that last erupted 66 million years ago. Three lava flows have been sampled at Nintoku Seamount; the flows are almost all alkalic (subaerial) lava. It is 56.2 million years old.
Yuryaku Seamount is a seamount and guyot (flat-topped) located northwest of Hawaii. It is located a little southwest of the V-shaped bend separating the Emperor Seamounts from the older Hawaiian islands, all of the Hawaiian-Emperor seamount chain in the North Pacific Ocean.
Colahan Seamount is a seamount lying within the Hawaiian–Emperor seamount chain in the northern Pacific Ocean. It erupted 37–40 million years ago.
Abbott Seamount is a seamount lying within the Hawaiian-Emperor seamount chain in the northern Pacific Ocean. It erupted 36-40 million years ago.
Kanmu Seamount is a seamount lying within the Hawaiian-Emperor seamount chain in the Pacific Ocean. The last eruption of Kanmu Seamount is unknown.
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