The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an

archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arch ...

of eight major

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An isla ...

s, several

atoll An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can gro ...

s, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost

Kure Atoll Kure Atoll (; haw, Hōlanikū, translation=bringing forth heaven; haw, Mokupāpapa, translation=flat island, label=none) or Ocean Island is an atoll in the Pacific Ocean west-northwest of Midway Atoll in the Northwestern Hawaiian Islands ...

. Formerly the group was known to Europeans and Americans as the Sandwich Islands, a name that

James Cook James Cook (7 November 1728 Old Style date: 27 October – 14 February 1779) was a British explorer, navigator, cartographer, and captain in the British Royal Navy, famous for his three voyages between 1768 and 1779 in the Pacific Ocean and ...

chose in honor of the 4th Earl of Sandwich, the then First Lord of the Admiralty. Cook came across the islands by chance when crossing the Pacific Ocean on his Third Voyage in 1778, on board HMS ''Resolution''; he was later killed on the islands on a return visit. The contemporary name of the islands, dating from the 1840s, is derived from the name of the largest island,

Hawaii Island Hawaii ( ; haw, Hawaii ) is the largest island in the United States, located in the state of Hawaii. It is the southeasternmost of the Hawaiian Islands, a chain of volcanic islands in the North Pacific Ocean. With an area of , it has 63% of t ...

. Hawaii sits on the

Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and I ...

and is the only U.S. state that is not geographically connected to North America. It is part of the

Polynesia Polynesia () "many" and νῆσος () "island"), to, Polinisia; mi, Porinihia; haw, Polenekia; fj, Polinisia; sm, Polenisia; rar, Porinetia; ty, Pōrīnetia; tvl, Polenisia; tkl, Polenihia (, ) is a subregion of Oceania, made up of ...

subregion of

Oceania Oceania (, , ) is a geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern and Western hemispheres, Oceania is estimated to have a land area of and a population of around 44.5 million ...

. The state of

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

occupies the archipelago almost in its entirety (including the mostly uninhabited

Northwestern Hawaiian Islands The Northwestern Hawaiian Islands or Leeward Hawaiian Islands are a series of islands and atolls in the Hawaiian island chain located northwest (in some cases, far to the northwest) of the islands of Kauai and Niihau. Politically, they are all ...

), with the sole exception of

Midway Island Midway Atoll (colloquial: Midway Islands; haw, Kauihelani, translation=the backbone of heaven; haw, Pihemanu, translation=the loud din of birds, label=none) is a atoll in the North Pacific Ocean. Midway Atoll is an insular area of the Unit ...

, which also belongs to the United States, as one of its unincorporated territories within the

United States Minor Outlying Islands The United States Minor Outlying Islands is a statistical designation defined by the International Organization for Standardization's ISO 3166-1 code. The entry code is ISO 3166-2:UM. The minor outlying islands and groups of islands consist ...

. The Hawaiian Islands are 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. The islands are about from the nearest continent.

Islands and reefs

The date of the first settlements of the Hawaiian Islands is a topic of continuing debate.

Archaeological Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscap ...

evidence seems to indicate a settlement as early as 124 AD.

Captain Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police department, election precinct, e ...

, RN, visited the islands on January 18, 1778, and named them the "Sandwich Islands" in honor of The 4th Earl of Sandwich, who as the First Lord of the Admiralty was one of his sponsors. This name was in use until the 1840s, when the local name "Hawaii" gradually began to take precedence. The Hawaiian Islands have a total land area of . Except for Midway, which is an unincorporated territory of the United States, these islands and islets are administered as

—the 50th state of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

Major islands

The eight major islands of Hawaii (Windward Islands) are listed above. All 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 are just a few: * Kaʻula *

Kāohikaipu Kāohikaipu (also known as Black Rock) is an islet located in Honolulu County, Hawaii. It is situated 0.6 miles away from nearby Mānana Island (Rabbit Island). The total size of Kāohikaipu is 11 acres. Its formation was due to the Honolulu Vol ...

Lehua Lehua Island is a small, crescent-shaped island in the Hawaiian islands, north of Niihau, due west of Kauai. The uninhabited, barren island is a tuff cone which is part of the active Niihau volcano. Lehua was one of the first five isl ...

* Mānana * Mōkōlea Rock * Mokolii * Moku Manu * Mokuauia * Moku o Loʻe * Moku Ola * Mokuʻumeʻume * Molokini *

Nā Mokulua Nā Mokulua, or just Mokulua (meaning, in Hawaiian, "the two islands") are two islets off the windward coast of Oahu in the Hawaiian Islands. The islets are often photographed and are located about 0.75 miles off Kaʻōhao (Lanikai), a neighborho ...

Partial islands, atolls, reefs

Partial islands, atolls, reefs (west of Niihau are uninhabited except Midway Atoll) form the

(Leeward Islands): *

Nihoa Nihoa (; haw, Nīhoa ), also known as Bird Island or Moku Manu, is the tallest of ten islands and atolls in the uninhabited Northwestern Hawaiian Islands (NWHI). The island is located at the southern end of the NWHI chain, southeast of ...

(Mokumana) * Necker (Mokumanamana) * French Frigate Shoals (Kānemilohai) *

Gardner Pinnacles The Gardner Pinnacles ( haw, Pūhāhonu) are two barren rock outcrops surrounded by a reef and located in the Northwestern Hawaiian Islands at . The volcano is northwest of Honolulu and from French Frigate Shoals. The total area of the two ...

(Pūhāhonu) * Maro Reef (Nalukākala) * Laysan (Kauō) * Lisianski Island (Papaāpoho) * Pearl and Hermes Atoll (Holoikauaua) *

Midway Atoll Midway Atoll (colloquial: Midway Islands; haw, Kauihelani, translation=the backbone of heaven; haw, Pihemanu, translation=the loud din of birds, label=none) is a atoll in the North Pacific Ocean. Midway Atoll is an insular area of the Unit ...

(Pihemanu) *

(Mokupāpapa)

Geology

This chain of islands, or

, developed as the

slowly moved northwestward over a hotspot in the Earth's mantle at a rate of approximately 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 Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

. 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,

, is the oldest at approximately 28 million years (Ma); while the southeasternmost island,

, is approximately 0.4 Ma (400,000 years). The only active volcanism in the last 200 years has been on the southeastern island, Hawaii, and on the submerged but growing volcano to the extreme southeast, Kamaʻehuakanaloa (formerly Loihi). The Hawaiian Volcano Observatory of the

USGS The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

documents recent volcanic activity and provides images and interpretations of the volcanism.

Kīlauea Kīlauea ( , ) is an active shield volcano in the Hawaiian Islands. Located along the southeastern shore of the Big Island of Hawaii, the volcano is between 210,000 and 280,000 years old and emerged above sea level about 100,000 years ago. His ...

had been erupting nearly continuously since 1983 when it stopped August 2018. Almost all of the

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natura ...

of the hotspot has the composition of

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

, and so the Hawaiian volcanoes are composed almost entirely of this igneous rock. There is very little coarser-grained

gabbro Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is ...

and

diabase Diabase (), also called dolerite () or microgabbro, is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. Diabase dikes and sills are typically shallow intrusive bodies and often exhibit fine-grain ...

. Nephelinite is exposed on the islands but is extremely rare. The majority of eruptions in Hawaii 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. Hawaii 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 A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more vi ...

on the Earth. The measurement from sea level to summit is more than , from sea level to sea floor about .

Earthquakes

The Hawaiian Islands have many

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fr ...

s, generally caused by volcanic activity. Most of the early earthquake monitoring took place in Hilo, by missionaries Titus Coan, Sarah J. Lyman and her family. Between 1833 and 1896, approximately 4 or 5 earthquakes were reported per year. Hawaii accounted for 7.3% of the United States' reported earthquakes with a magnitude 3.5 or greater from 1974 to 2003, with a total 1533 earthquakes. Hawaii ranked as the state with the third most earthquakes over this time period, after

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...

and

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. On October 15, 2006, there was an earthquake with a magnitude of 6.7 off the northwest coast of the island of Hawaii, near the

Kona Kona or KONA may refer to: People *Kona (surname) *Dilshad Nahar Kona, Bangladeshi singer also known as Kona Television * ''Kona'' (TV series), a Kenyan telenovela that premiered in 2013 Locations * Kona, Kentucky * Kona, North Carolina * Ko ...

area of the big island. The initial earthquake was followed approximately five minutes later by a magnitude 5.7

aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousa ...

. Minor-to-moderate damage was reported on most of the Big Island. Several major roadways became impassable from rock slides, and effects were felt as far away as

Honolulu Honolulu (; ) is the capital and largest city of the U.S. state of Hawaii, which is in the Pacific Ocean. It is an unincorporated county seat of the consolidated City and County of Honolulu, situated along the southeast coast of the isla ...

, Oahu, nearly from the epicenter. Power outages lasted for several hours to days. Several water mains ruptured. No deaths or life-threatening injuries were reported. On May 4, 2018, there was a 6.9 earthquake in the zone of volcanic activity from

. Earthquakes are monitored by the Hawaiian Volcano Observatory run by the

Tsunamis

The Hawaiian Islands are subject to

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater exp ...

s, great

wave In physics, mathematics, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (re ...

s that strike the shore. Tsunamis are most often caused by

s somewhere in the Pacific. The waves produced by the earthquakes travel at speeds of and can affect coastal regions thousands of miles (kilometers) away. Tsunamis may also originate from the Hawaiian Islands. Explosive volcanic activity can cause tsunamis. The island of

Molokai Molokai , or Molokai (), is the fifth most populated of the eight major islands that make up the Hawaiian Islands archipelago in the middle of the Pacific Ocean. It is 38 by 10 miles (61 by 16 km) at its greatest length and width with a us ...

had a catastrophic collapse or debris avalanche over a million years ago; this underwater landslide likely caused tsunamis. The

Hilina Slump The Hilina Slump, on the south flank of the Kilauea Volcano, Kīlauea Volcano on the southeast coast of the Hawaii (island), Big Island of Hawaii, Hawaiʻi, is the most notable of several landslides that ring each of the Hawaiian Islands. These ...

on the island of Hawaii is another potential place for a large landslide and resulting tsunami. The city of Hilo on the Big Island has been most affected by tsunamis, where the in-rushing water is accentuated by the shape of Hilo Bay. Coastal cities have tsunami warning sirens. A tsunami resulting from an earthquake in Chile hit the islands on February 27, 2010. It was relatively minor, but local emergency management officials utilized the latest technology and ordered evacuations in preparation for a possible major event. The Governor declared it a "good drill" for the next major event. A tsunami resulting from an earthquake in Japan hit the islands on March 11, 2011. It was relatively minor, but local officials ordered evacuations in preparation for a possible major event. The tsunami caused about $30.1 million in damages.

History

Ecology

The islands are home to a multitude of

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

species. Since human settlement, first by

Polynesians Polynesians form an ethnolinguistic group of closely related people who are native to Polynesia (islands in the Polynesian Triangle), an expansive region of Oceania in the Pacific Ocean. They trace their early prehistoric origins to Island Sou ...

, non native trees, plants, and animals were introduced. These included species such as rats and pigs, that have preyed on native birds and invertebrates that initially evolved in the absence of such predators. The growing population of humans has also led to deforestation,

forest degradation Forest degradation is a process in which the biological wealth of a forest area is permanently diminished by some factor or by a combination of factors. "This does not involve a reduction of the forest area, but rather a quality decrease in its c ...

, treeless grasslands, and

environmental degradation Environmental degradation is the deterioration of the environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; and pollution. It is defin ...

. As a result, many species which depended on forest habitats and food became extinct—with many current species facing extinction. As humans cleared land for farming, monocultural crop production replaced multi-species systems. The arrival of the

Europeans Europeans are the focus of European ethnology, the field of anthropology related to the various ethnic groups that reside in the states of Europe. Groups may be defined by common genetic ancestry, common language, or both. Pan and Pfeil (20 ...

had a more significant impact, with the promotion of large-scale single-species export agriculture and livestock grazing. This led to increased clearing of forests, and the development of towns, adding many more species to the

list of extinct animals of the Hawaiian Islands This is a list of Hawaiian species extinct in the Holocene that covers extinctions from the Holocene epoch, a geologic epoch that began about 11,650 years before present (about 9700 BCE) and continues to the present day. The Hawaiian Island ...

. , many of the remaining endemic species are considered endangered.

National Monument

On June 15, 2006, President George W. Bush issued a public proclamation creating Papahānaumokuākea Marine National Monument under the

Antiquities Act The Antiquities Act of 1906 (, , ), is an act that was passed by the United States Congress and signed into law by Theodore Roosevelt on June 8, 1906. This law gives the President of the United States the authority to, by presidential pro ...

of 1906. The Monument encompasses the northwestern Hawaiian Islands and surrounding waters, forming the largest marine wildlife reserve in the world. In August 2010,

UNESCO The United Nations Educational, Scientific and Cultural Organization is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) aimed at promoting world peace and security through international coope ...

World Heritage Committee The World Heritage Committee selects the sites to be listed as UNESCO World Heritage Sites, including the World Heritage List and the List of World Heritage in Danger, defines the use of the World Heritage Fund and allocates financial assistance ...

added Papahānaumokuākea to its list of

World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for ...

s. On August 26, 2016, President

Barack Obama Barack Hussein Obama II ( ; born August 4, 1961) is an American politician who served as the 44th president of the United States from 2009 to 2017. A member of the Democratic Party (United States), Democratic Party, Obama was the first Af ...

greatly expanded Papahānaumokuākea, quadrupling it from its original size.

Climate

The Hawaiian Islands are

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

but experience many different climates, depending on altitude and surroundings. The islands receive most rainfall from the trade winds on their north and east flanks (the windward side) as a result of

orographic precipitation Orography is the study of the topographic relief of mountains, and can more broadly include hills, and any part of a region's elevated terrain. Orography (also known as ''oreography'', ''orology'' or ''oreology'') falls within the broader discip ...

. Coastal areas in general and especially the south and west flanks, or leeward sides, tend to be drier. In general, the lowlands of Hawaiian Islands receive most of their precipitation during the winter months (October to April). Drier conditions generally prevail from May to September. The

tropical storm A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...

s, and occasional

hurricane A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...

s, tend to occur from July through November. During the summer months the average temperature is about 84 °F (29 °C), in the winter months it is approximately 78,8 °F (26 °C). As the temperature is relatively constant over the year the probability of dangerous thunderstorms is approximately low.