TheHawaiian Islands (Hawaiian:Mokupuni Hawaiʻi) are anarchipelago of eight majorvolcanic islands, severalatolls, and numerous smallerislets in theNorth Pacific Ocean, extending some 1,500 miles (2,400 kilometers) from theisland of Hawaiʻi in the south to northernmostKure Atoll. Formerly called theSandwich Islands[a] by Europeans, the present name for the archipelago is derived from the name of its largest island, Hawaiʻi.
The Hawaiian Islands have a total land area of 6,423.4 square miles (16,636.5 km2). Except for Midway, which is anunincorporated unorganized territory of the United States, these islands and islets are administered asHawaii—the 50th state of the United States.[1]
Hawaiian Islands from space.[11]3-D perspective view of the southeastern Hawaiian Islands, with the white summits ofMauna Loa (4,170 m or 13,680 ft high) andMauna Kea (4,207.3 m or 13,803 ft high). The islands are the tops of massive volcanoes, the bulk of which lie below the sea surface. Ocean depths are colored from violet (5,750 m or 18,860 ft deep northeast ofMaui) and indigo to light gray (shallowest). Historical lava flows are shown in red, erupting from the summits and rift zones of Mauna Loa,Kilauea, andHualalai volcanoes onHawaiʻi.Aerial view of Lēʻahi orDiamond Head, Oʻahu
The state of Hawaii counts 137 "islands" in the Hawaiian Chain.[12] 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:
A composite satellite image fromNASA of the Hawaiian Islands taken fromouter space. Click on the image for a larger view that shows the main islands and the extendedarchipelago.
Eruptions from theHawaii hotspot left a trail of underwater mountains across the Pacific over millions of years, called theEmperor Seamounts.
This chain of islands, orarchipelago, developed as thePacific Plate slowly moved northwestward over ahotspot in theEarth'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 toerosion. The age of the archipelago has been estimated using potassium-argon dating methods.[13] From this study and others,[14][15] 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). TheHawaiian Volcano Observatory of theUSGS 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 themagma of the hotspot has the composition ofbasalt, and so the Hawaiian volcanoes are composed almost entirely of this igneous rock. There is very little coarser-grainedgabbro anddiabase.Nephelinite is exposed on the islands but is extremely rare. The majority of eruptions in Hawaiʻi areHawaiian-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 largestshield 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).[16]
The Hawaiian Islands have manyearthquakes, generally triggered by and related to volcanic activity. Seismic activity, as a result, is currently highest in the southern part of the chain. Both historical and modern earthquake databases have correlated higher magnitude earthquakes with flanks of active volcanoes, such as Mauna Loa and Kilauea. The combination of erosional forces, which cause slumping and landslides, with the pressure exerted by rising magma put a great amount of stress on the volcanic flanks. The stress is released when the slope fails, or slips, causing an earthquake. This type of seismicity is unique because the forces driving the system are not always consistent over time, since rates of volcanic activity fluctuate. Seismic hazard near active, seaward volcanic flanks is high, partially because of the especially unpredictable nature of the forces that trigger earthquakes, and partially because these events occur at relatively shallow depths. Flank earthquakes typically occur at depths ranging from 5 to 20 km, increasing the hazard to local infrastructure and communities.[17] Earthquakes and landslides on the island chain have also been known to causetsunamis.
Most of the early earthquake monitoring took place inHilo, by missionariesTitus Coan and Sarah J. Lyman and her family. Between 1833 and 1896, approximately 4 or 5 earthquakes were reported per year.[18] Today, earthquakes are monitored by theHawaiian Volcano Observatory run by theUSGS.
Hawaii accounted for 7.3% of the United States' reported earthquakes with amagnitude 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, afterAlaska andCalifornia.[19]
On October 15, 2006, there was an earthquake with a magnitude of 6.7 off the northwest coast of the island of Hawaii, near theKona area. The initial earthquake was followed approximately five minutes later by a magnitude 5.7aftershock. 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 asHonolulu, Oahu, nearly 150 miles (240 km) from theepicenter. 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 a6.9 earthquake in the zone of volcanic activity fromKīlauea.
Aftermath of the1960 Chilean tsunami inHilo, Hawaiʻi, where the tsunami left 61 people dead and 282 seriously injured. The waves reached 35 feet (11 m) high.
The Hawaiian Islands are subject totsunamis, greatwaves that strike the shore. Tsunamis are most often caused byearthquakes somewhere in the Pacific. The waves produced by the earthquakes travel at speeds of 400–500 miles per hour (600–800 km/h) 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 ofMolokaʻi had a catastrophic collapse ordebris avalanche over a million years ago; this underwater landslide likely caused tsunamis. TheHilina Slump on theisland of Hawaiʻi is another potential place for a large landslide and resulting tsunami.
The city ofHilo on the Big Island has been most affected by tsunamis, where the in-rushing water is accentuated by the shape ofHilo Bay. Coastal cities have tsunami warning sirens.
A tsunami resulting from anearthquake 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 anearthquake 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.[20]
Lava erupting from Kīlauea, one of six active volcanoes in the Hawaiian islands. Kīlauea is the most active, erupting nearly continuously from 1983 to 2018.
Only the two Hawaiian islands furthest to the southeast have active volcanoes:Haleakalā on Maui, andMauna Loa,Mauna Kea,Kilauea, andHualalai, all on the Big Island. The volcanoes on the remaining islands are extinct as they are no longer over the Hawaii hotspot. TheKamaʻehuakanaloa Seamount is an active submarine volcano that is expected to become the newest Hawaiian island when it rises above the ocean's surface in 10,000–100,000 years.[21]Hazards from these volcanoes include lava flows that can destroy and bury the surrounding surface, volcanic gas emissions, earthquakes and tsunamis listed above, submarine eruptions affecting the ocean, and the possibility of an explosive eruption.[22]
Death of the first European visitor to the Hawaiian Islands, CaptainJames Cook, atKealakekua Bay on February 14, 1779
Hawaii was first discovered and settled by explorers fromTahiti or theMarquesas Islands. The date of the first settlements is the subject of continued debate.[23]Kirch's textbooks on Hawaiian archeology date the first Polynesian settlements to about 300 C.E., although his more recent estimates are as late as 600.[23] More recent surveys ofcarbon-dating evidence put the arrival of the first settlers at around 940–1130 C.E.[24]
The first recorded and sustained contact with Europeans occurred by chance whenBritish explorerJames Cook sighted the islands in January 1778 during histhird voyage of exploration. Aided by European military technology,Kamehameha I conquered and unified the islands for the first time, establishing theKingdom of Hawaii in 1795. The kingdom became prosperous and important for its agriculture and strategic location in the Pacific.
American immigration, led by Protestantmissionaries, andNative Hawaiian emigration, mostly on whaling ships but also in high numbers as indentured servants and as forced labor, began almost immediately after Cook's arrival. Americans established plantations to grow crops for export. Their farming methods required substantial labor. Waves of permanent immigrants came fromJapan,China, andthe Philippines to labor in the cane and pineapple fields. The government of Japan organized and gave special protection to its people, who comprised about 25 percent of the Hawaiian population by 1896. The Hawaiian monarchy encouraged this multi-ethnic society, initially establishing a constitutional monarchy in 1840 that promised equal voting rights regardless of race, gender, or wealth.
The population of Native Hawaiians declined precipitously from an unknown number prior to 1778 (estimated to be around 300,000). It fell to around 142,000 in the 1820s based on a census conducted by American missionaries, 82,203 in the 1850 Hawaiian Kingdom census, 40,622 in the final Hawaiian Kingdom census of 1890, 39,504 in the sole census by the Republic of Hawaii in 1896, and 37,656 in the first census conducted by the United States in 1900. Thereafter the Native Hawaiian population in Hawaii increased with every census, reaching 680,442 in 2020 (including people of mixed heritage).
The islands are home to a multitude ofendemic species. Since human settlement, first byPolynesians, 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, especially through European and American colonization and development, has also led todeforestation,forest degradation, treeless grasslands, andenvironmental degradation.[25] 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 with the importation of industrialized farming practices through European and American encroachment,monocultural crop production replacedmulti-species systems.[25]
'I'iwi (Drepanis coccinea) and other endemic species have been heavily impacted by human activity, such as invasive species and habitat loss
The arrival of theEuropeans 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 thelist of extinct animals of the Hawaiian Islands. As of 2009[update], many of the remaining endemic species are consideredendangered.[26]
The Hawaiian Islands aretropical but experience many different climates, depending on altitude and surroundings.[34] The islands receive most rainfall from thetrade winds on their north and east flanks (the windward side) as a result oforographic precipitation.[34] Coastal areas in general and especially the south and west flanks, orleeward sides, tend to be drier.[34]
In general, the lowlands of Hawaiian Islands receive most of their precipitation during the winter months (October to April).[34] Drier conditions generally prevail from May to September.[34] Thetropical storms, and occasionalhurricanes, tend to occur from July through November.[34]
During the summer months the average temperature is about 84 °F (29 °C), in the winter months it is approximately 79 °F (26 °C). As the temperature is relatively constant over the year the probability of dangerous thunderstorms is approximately low.[35]
^"Hawai'i Facts & Figures"(PDF).state web site. State of Hawaii Dept. of Business, Economic Development & Tourism. December 2009. Archived fromthe original(PDF) on October 22, 2008. RetrievedMay 23, 2010.
^"Mauna Loa Earth's Largest Volcano".Hawaiian Volcano Observatory web site. United States Geological Survey. February 2006. Archived fromthe original on November 17, 2014. RetrievedDecember 9, 2009.
^Athens, J. S. (2014). "A paleoenvironment and archeological model-based age estimate for the colonization of Hawai'i".American Antiquity.79 (1):144–155.doi:10.7183/0002-7316.79.1.144.S2CID163179921.
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