Hawaiian Islands

Hawaiian Islands

Overview
The Hawaiian Islands are an archipelago
Archipelago
An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...

 of eight major island
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

s, several atoll
Atoll
An atoll is a coral island that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu OED...

s, numerous smaller islet
Islet
An islet is a very small island.- Types :As suggested by its origin as islette, an Old French diminutive of "isle", use of the term implies small size, but little attention is given to drawing an upper limit on its applicability....

s, and undersea seamount
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...

s in the North Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, extending some 1,500 miles (2,400 km) from the island of Hawaii
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

 in the south to northernmost Kure Atoll
Kure Atoll
Kure Atoll or Ocean Island is an atoll in the Pacific Ocean beyond Midway Atoll in the Northwestern Hawaiian Islands at . The only land of significant size is called Green Island and is habitat for hundreds of thousands of seabirds...

 (the northwesternmost island in Hawaii is Green Island, which is joined to the Kure Atoll). Excluding Midway
Midway Atoll
Midway Atoll is a atoll in the North Pacific Ocean, near the northwestern end of the Hawaiian archipelago, about one-third of the way between Honolulu, Hawaii, and Tokyo, Japan. Unique among the Hawaiian islands, Midway observes UTC-11 , eleven hours behind Coordinated Universal Time and one hour...

, which is an unincorporated territory of the United States, the Hawaiian Islands form the U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 state of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

.
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Encyclopedia
The Hawaiian Islands are an archipelago
Archipelago
An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...

 of eight major island
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

s, several atoll
Atoll
An atoll is a coral island that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu OED...

s, numerous smaller islet
Islet
An islet is a very small island.- Types :As suggested by its origin as islette, an Old French diminutive of "isle", use of the term implies small size, but little attention is given to drawing an upper limit on its applicability....

s, and undersea seamount
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...

s in the North Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, extending some 1,500 miles (2,400 km) from the island of Hawaii
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

 in the south to northernmost Kure Atoll
Kure Atoll
Kure Atoll or Ocean Island is an atoll in the Pacific Ocean beyond Midway Atoll in the Northwestern Hawaiian Islands at . The only land of significant size is called Green Island and is habitat for hundreds of thousands of seabirds...

 (the northwesternmost island in Hawaii is Green Island, which is joined to the Kure Atoll). Excluding Midway
Midway Atoll
Midway Atoll is a atoll in the North Pacific Ocean, near the northwestern end of the Hawaiian archipelago, about one-third of the way between Honolulu, Hawaii, and Tokyo, Japan. Unique among the Hawaiian islands, Midway observes UTC-11 , eleven hours behind Coordinated Universal Time and one hour...

, which is an unincorporated territory of the United States, the Hawaiian Islands form the U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 state of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

. Once known as the "Sandwich Islands", the archipelago now takes its name from the largest island in the cluster.

The islands are the exposed peaks of a great undersea mountain range known as the Hawaiian-Emperor seamount chain
Hawaiian-Emperor seamount chain
The Hawaiian–Emperor seamount chain is composed of the Hawaiian ridge, consisting of the islands of the Hawaiian chain northwest to Kure Atoll, and the Emperor Seamounts, a vast underwater mountain region of islands and intervening seamounts, atolls, shallows, banks and reefs along a line trending...

, formed by volcanic
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 activity over a hotspot
Hotspot (geology)
The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them...

 in the Earth's mantle. The Hawaiian islands are about 1860 miles (2,993.4 km) from the nearest continent.

Islands and reefs



Captain James Cook
James Cook
Captain James Cook, FRS, RN was a British explorer, navigator and cartographer who ultimately rose to the rank of captain in the Royal Navy...

 visited the islands on January 18, 1778 and named them the "Sandwich Islands" in honor of John Montagu, 4th Earl of Sandwich
John Montagu, 4th Earl of Sandwich
John Montagu, 4th Earl of Sandwich, PC, FRS was a British statesman who succeeded his grandfather, Edward Montagu, 3rd Earl of Sandwich, as the Earl of Sandwich in 1729, at the age of ten...

, who was one of his sponsors as the First Lord of the Admiralty.

The Hawaiian Islands have a total land area of 6423.4 square miles (16,636.5 km²). Except for Midway
Midway Atoll
Midway Atoll is a atoll in the North Pacific Ocean, near the northwestern end of the Hawaiian archipelago, about one-third of the way between Honolulu, Hawaii, and Tokyo, Japan. Unique among the Hawaiian islands, Midway observes UTC-11 , eleven hours behind Coordinated Universal Time and one hour...

, which is an unincorporated territory of the United States, these islands and islets are administered as the state of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

 — the 50th state of the United States of America
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

.

Main islands


The eight main islands of Hawaii (also called the Hawaiian Windward Islands) are listed here. All except Kahoolawe are inhabited.

Smaller islands, atolls, reefs


Smaller islands, atolls, and reefs (all west of Niihau and uninhabited) form the Northwestern Hawaiian Islands
Northwestern Hawaiian Islands
The Northwestern Hawaiian Islands or the Leeward Islands are the small islands and atolls in the Hawaiian island chain located northwest of the islands of Kauai and Niihau. They are administered by the U.S. state of Hawaii except Midway Atoll, which has temporary residential facilities and is...

, or Hawaiian Leeward Islands:
  • Nihoa
    Nihoa
    Nihoa , also known as Bird Island or Moku Manu, is the largest and tallest of ten islands and atolls in the uninhabited Northwestern Hawaiian Islands . The island is located at the southern end of the NWHI chain, southeast of Necker Island...

     (Mokumana)
  • Necker (Mokumanamana)
  • French Frigate Shoals
    French Frigate Shoals
    The French Frigate Shoals is the largest atoll in the Northwestern Hawaiian Islands. Its name commemorates French explorer Jean-François de La Pérouse, who nearly lost two frigates when attempting to navigate the shoals...

     (Kānemilohai)
  • Gardner Pinnacles
    Gardner Pinnacles
    The Gardner Pinnacles are two barren rock outcrops surrounded by a reef and located in the Hawaiian Islands at , northwest of Honolulu and French Frigate Shoals. The total area of the two small islets—remnants of an ancient volcano—is . Its highest peak has a commanding height of 170...

     (Pūhāhonu)
  • Maro Reef
    Maro Reef
    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 , it is the largest coral reef in the Northwestern Hawaiian Islands...

     (Nalukākala)
  • Laysan
    Laysan
    Laysan , located northwest of Honolulu at N25° 42' 14" W171° 44' 04", is one of the Northwestern Hawaiian Islands. It comprises one land mass of , about 1 by 1.5 miles in size . It is an atoll of sorts, although the land completely surrounds a shallow central lake some above sea level that has...

     (Kauō)
  • Lisianski Island
    Lisianski Island
    Lisianski Island is one of the Northwestern Hawaiian Islands, with a land area of and a maximum elevation of above sea level. Honolulu is away, to the southeast. Linked to Lisianski are the extensive Neva Shoals...

     (Papaāpoho)
  • Pearl and Hermes Atoll
    Pearl and Hermes Atoll
    The Pearl and Hermes Atoll , is part of the Northwestern Hawaiian Islands. Named after two English whaleships, the Pearl and the Hermes, that wrecked there in 1822, a few, small, sandy islands exist, contained within a lagoon and surrounded by a coral reef. These islands are devoid of vegetation,...

     (Holoikauaua)
  • Midway Atoll
    Midway Atoll
    Midway Atoll is a atoll in the North Pacific Ocean, near the northwestern end of the Hawaiian archipelago, about one-third of the way between Honolulu, Hawaii, and Tokyo, Japan. Unique among the Hawaiian islands, Midway observes UTC-11 , eleven hours behind Coordinated Universal Time and one hour...

     (Pihemanu) (temporary residential facilities)
  • Kure Atoll
    Kure Atoll
    Kure Atoll or Ocean Island is an atoll in the Pacific Ocean beyond Midway Atoll in the Northwestern Hawaiian Islands at . The only land of significant size is called Green Island and is habitat for hundreds of thousands of seabirds...

     (Mokupāpapa)

Islets


The state of Hawaii counts 137 "islands" in the Hawaiian chain, and the Midway Islands. This number includes all minor islands and islet
Islet
An islet is a very small island.- Types :As suggested by its origin as islette, an Old French diminutive of "isle", use of the term implies small size, but little attention is given to drawing an upper limit on its applicability....

s offshore of the main islands (listed above) and individual islets in each atoll. These are just a few:
  • Ford Island
    Ford Island
    Ford Island is located in the middle of Pearl Harbor, Hawaii. It is connected to the main island by the Ford Island Bridge. Before the bridge was built, Ford Island could only be reached by a ferry boat which ran at hourly intervals for cars and foot passengers. The island houses several naval...

     (Mokuumeume)
  • Lehua
    Lehua
    Lehua is a small, crescent-shaped island in the Hawaiian islands, only north of Niihau, due west of Kauai. The uninhabited, barren island is a tuff cone which is part of the extinct Niihau volcano....

  • Kaʻula
  • Kaohikaipu
  • Manana
    Manana
    Mānana Island is an uninhabited islet located off Kaupō Beach, near Makapuu at the eastern end of the Island of Oahu in the Hawaiian Islands. In the Hawaiian language, mānana means "buoyant"...

  • Mōkōlea Rock
    Mokolea Rock
    Mōkōlea Rock is an islet in Kailua Bay along the windward coast of Oahu in Hawaii and located east of Marine Corps Base Hawaii . Like most of the small islets off the coastline of a major island in the Hawaiian Islands, Mōkōlea is a State Bird Sanctuary containing many types of birds.The islet is...

  • Nā Mokulua
    Na Mokulua
    Nā Mokulua are two islets off the windward coast of O‘ahu in the Hawaiian Islands. They are also commonly known as "The Moks" or the "Twin Islands". The islets are located about .75 miles off Lanikai, a neighborhood of Kailua, Hawai‘i and are often photographed. The larger island is Moku Nui and...

  • Molokini
    Molokini
    Molokini is a crescent-shaped, partially submerged volcanic crater which forms a small islet located in Alalakeiki Channel between the islands of Maui and Kahoolawe, part of Maui County in Hawaii. It has an area of , a diameter of about , and is located about west of Makena State Park and south...

  • Mokolii
    Mokolii
    Mokolii is a , basalt island offshore of Kualoa Point, Oahu, in Kāne'ohe Bay, Hawaii, at . Geologically, it used to be connected to Oahu before erosion cut it off. It is also known as "Chinaman's Hat" for its likeness to the straw hats Chinese immigrants wore...

  • Moku Manu
    Moku Manu
    Moku Manu, or "Bird Island" in the Hawaiian language, is an offshore islet of Oahu, three-quarters of a mile off Mokapu Peninsula. Moku Manu and an adjacent small islet are connected by an underwater dike. The island was formed from debris flung from a vent of the nearby Kailua Volcano. Its highest...

  • Moku Ola
    Coconut Island (Hawaii Island)
    Coconut Island, or Moku Ola is a small island in Hilo Bay, just offshore from Liliʻuokalani Gardens, in Hilo, off the island of Hawaiʻi in the state of Hawaii, USA. It is a small park, and is connected to the main island via a footbridge...

     (Coconut Island, Hawaii)
  • Moku o Loʻe
    Coconut Island
    Coconut Island, or Moku o Loe, is a 28-acre island in Kāne'ohe Bay off the island of O'ahu in the state of Hawai'i, USA. It is a marine research facility of the Hawai`i Institute of Marine Biology of the University of Hawai`i....

     (Coconut Island, Oahu)
  • Sand Island
    Sand Island (Hawaii)
    Sand Island, formerly known as Quarantine Island, is a small island within the city of Honolulu, Hawaii, United States. The island lies at the entrance to Honolulu Harbor.-History:...

  • Grass Island
    Grass Island
    Grass Island can refer to* Grass Island, Hong Kong* Grass Island * Grass Island * Grass Island, a small island located in the Midway Island chain. The coordinates are: 27°46'28.31 N 175°54'24.38 W...


Geology



The chain of islands or archipelago
Archipelago
An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...

 formed as the Pacific plate
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

 moved slowly northwestward over a hotspot
Hotspot (geology)
The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them...

 in the Earth's mantle at about 32 miles (51.5 km) per million years.
Hence the islands in the northwest of the archipelago are older and typically smaller, due to longer exposure to erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

. The age of the archipelago has been estimated using potassium-argon dating methods. From this study and others, it is estimated that the northwestern most island, the Kure Atoll
Kure Atoll
Kure Atoll or Ocean Island is an atoll in the Pacific Ocean beyond Midway Atoll in the Northwestern Hawaiian Islands at . The only land of significant size is called Green Island and is habitat for hundreds of thousands of seabirds...

, is the oldest at approximately 28 million years (Ma); while the southeastern most island, Hawaii
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

, is approximately 0.4 Ma (400,000 years). The only active volcanism in the last 200 years has been on the southeastern island, Hawaii
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

, and on the submerged but growing volcano at the extreme southeast, Loihi. The Hawaiian Volcano Observatory
Hawaiian Volcano Observatory
The Hawaiian Volcano Observatory is a volcano observatory located at Uwekahuna Bluff on the rim of Kīlauea Caldera on the Island of Hawaii. The observatory monitors four active Hawaiian volcanoes: Kīlauea, Mauna Loa, Hualālai, and Haleakalā...

 of the U. S. Geological Survey documents recent volcanic activity and provides images and interpretations of the volcanism.

Almost all magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...

 created in the hotspot has the composition of basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

, and so the Hawaiian volcanoes are constructed almost entirely of this igneous rock and its coarse-grained equivalents, gabbro
Gabbro
Gabbro refers to a large group of dark, coarse-grained, intrusive mafic igneous rocks chemically equivalent to basalt. The rocks are plutonic, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....

 and diabase
Diabase
Diabase or dolerite is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro. In North American usage, the term diabase refers to the fresh rock, whilst elsewhere the term dolerite is used for the fresh rock and diabase refers to altered material...

. A few igneous rock types with compositions unlike basalt, such as nephelinite
Nephelinite
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene . If olivine is present, the rock may be classified as an olivine nephelinite. Nephelinite is dark in color and may resemble basalt in hand specimen...

, do occur on these islands but are extremely rare. The majority of eruptions in Hawaii are Hawaiian-type eruption
Hawaiian eruption
A Hawaiian eruption is a type of volcanic eruption where lava flows from the vent in a relative gentle, low level eruption, so called because it is characteristic of Hawaiian volcanoes. Typically they are effusive eruptions, with basaltic magmas of low viscosity, low content of gases, and high...

s 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 largest and youngest island in the chain, built from five volcanoes. Mauna Loa
Mauna Loa
Mauna Loa is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean, and the largest on Earth in terms of volume and area covered. It is an active shield volcano, with a volume estimated at approximately , although its peak is about lower than that...

, comprising over half of the Big Island, is the largest shield volcano
Shield volcano
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...

 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


The Hawaiian Islands have many earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

s, generally caused by volcanic activity. Most of the early earthquake monitoring took place in Hilo, by missionaries Titus Coan
Titus Coan
Titus Coan was an early American Christian Missionary to the Hawaiian Islands.-Early life and family:Titus Coan was born on February 1, 1801 in Killingworth, Connecticut, the son of Gaylord Coan and Tamza Nettleton. In June, 1831, he entered the Auburn Theological Seminary in Auburn, New York, and...

, Sarah J. Lyman and her family. From 1833 to 1896, approximately 4 or 5 earthquakes were reported per year.

Hawaii accounted for 7.3% of the United States' reported earthquakes with a magnitude
Richter magnitude scale
The expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake....

 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
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

 and California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

.
On Sunday, October 15, 2006, there was an earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

 with a magnitude of 6.7 off the northwest coast of the island of Hawaii
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

, near the Kona
Kona District, Hawaii
Kona is the name of a moku or district on the Big Island of Hawaii in the State of Hawaii. In the current system of administration of Hawaii County, the moku of Kona is divided into North Kona District and South Kona District . The term "Kona" is sometimes used to refer to its largest town,...

 area of the big island. The initial earthquake was followed approximately five minutes later by a magnitude 5.7 aftershock
Aftershock
An aftershock is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock...

. 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, Hawaii
Honolulu is the capital and the most populous city of the U.S. state of Hawaii. Honolulu is the southernmost major U.S. city. Although the name "Honolulu" refers to the urban area on the southeastern shore of the island of Oahu, the city and county government are consolidated as the City and...

, Oahu, nearly 150 miles (241.4 km) from the epicenter
Epicenter
The epicenter or epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or underground explosion originates...

. Power outages lasted for several hours to whole days. Several water mains ruptured. No deaths or life-threatening injuries were reported.

Earthquakes are monitored by the Hawaiian Volcano Observatory
Hawaiian Volcano Observatory
The Hawaiian Volcano Observatory is a volcano observatory located at Uwekahuna Bluff on the rim of Kīlauea Caldera on the Island of Hawaii. The observatory monitors four active Hawaiian volcanoes: Kīlauea, Mauna Loa, Hualālai, and Haleakalā...

 run by the USGS.

Tsunamis



The Hawaiian Islands are subject to tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

s, great wave
Wave
In physics, a wave is a disturbance that travels through space and time, accompanied by the transfer of energy.Waves travel and the wave motion transfers energy from one point to another, often with no permanent displacement of the particles of the medium—that is, with little or no associated mass...

s that strike the shore. Tsunamis are most often caused by earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

s somewhere in the Pacific. The waves produced by the earthquakes travel at speeds of 400 – and can affect coastal regions thousands of miles (kilometers) away.

Tsunamis may also initiate in the Hawaiian Islands. Explosive volcanic activity can cause tsunamis. The island of Molokai
Molokai
Molokai or Molokai is an island in the Hawaiian archipelago. It is 38 by 10 miles in size with a land area of , making it the fifth largest of the main Hawaiian Islands and the 27th largest island in the United States. It lies east of Oahu across the 25-mile wide Kaiwi Channel and north of...

 had a catastrophic collapse or debris avalanche over a million years ago; this underwater landslide likely caused tsunamis. The Hilina Slump
Hilina Slump
The Hilina Slump is a 5,000 cubic mile chunk of the big island of Hawaii on the south flank of the Kilauea volcano. Between 1990 and 1993, Global Positioning System measurements showed a southward displacement of the south flank of Kilauea up to approximately 10 centimeters per year...

 on the island of Hawaii
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

 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
Hilo Bay
Hilo Bay is a large bay located on the eastern coast of the island of Hawaii.-Description:The modern town of Hilo, Hawaii overlooks Hilo Bay, located at ....

. Coastal cities have tsunami warning sirens.

A tsunami resulting from an earthquake in Chile
2010 Chile earthquake
The 2010 Chile earthquake occurred off the coast of central Chile on Saturday, 27 February 2010, at 03:34 local time , having a magnitude of 8.8 on the moment magnitude scale, with intense shaking lasting for about three minutes. It ranks as the sixth largest earthquake ever to be recorded by a...

 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. It was declared a "good drill" for the next major event by the Governor.

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 $1 million in damages, almost all limited to the Kona coast of the Big Island.

Ecology

Related article: Endemism in the Hawaiian Islands
Endemism in the Hawaiian Islands
Located some 2,400 miles from the nearest continental shore, the Hawaiian Islands are the most isolated group of islands on the planet...

.


The endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...

 plant and animal species of the Hawaiian Islands developed in nearly complete isolation over about 70 million years. Prior to the human arrival, the only native mammal was the Hawaiian hoary bat
Hawaiian Hoary bat
The Hawaiian Hoary bat or Ōpeapea is a subspecies of the Hoary bat that is endemic to the Hawaiian Islands...

.

Human contact, first by Polynesians
Polynesians
The Polynesian peoples is a grouping of various ethnic groups that speak Polynesian languages, a branch of the Oceanic languages within the Austronesian languages, and inhabit Polynesia. They number approximately 1,500,000 people...

, introduced new trees, plants and animals. These included voracious species such as rats and pigs, who took a heavy toll on native birds and invertebrates that evolved in the absence of such predators. The growing population also brought deforestation, forest degradation, treeless grasslands, and environmental degradation. As a result, many species which depended on forest habitats and food went extinct. As humans cleared land for farming, monocultural crop production
Monoculture
Monoculture is the agricultural practice of producing or growing one single crop over a wide area. It is also known as a way of farming practice of growing large stands of a single species. It is widely used in modern industrial agriculture and its implementation has allowed for large harvests from...

 replaced multi-species systems
Polyculture
Polyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture...

.

The arrival of the European
European ethnic groups
The ethnic groups in Europe are the various ethnic groups that reside in the nations of Europe. European ethnology is the field of anthropology focusing on Europe....

s had a 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 more species to list of extinct animals of the Hawaiian Islands. As of 2009, many of the remaining endemic species are considered endangered.

National Monument



On June 15, 2006, President George W. Bush
George W. Bush
George Walker Bush is an American politician who served as the 43rd President of the United States, from 2001 to 2009. Before that, he was the 46th Governor of Texas, having served from 1995 to 2000....

 issued a public proclamation creating Papahānaumokuākea Marine National Monument under the Antiquities Act
Antiquities Act
The Antiquities Act of 1906, officially An Act for the Preservation of American Antiquities , is an act passed by the United States Congress and signed into law by Theodore Roosevelt on June 8, 1906, giving the President of the United States authority to, by executive order, restrict the use of...

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

Climate



Hawaii (state) is tropical
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately  N and the Tropic of Capricorn in the southern hemisphere at  S; these latitudes correspond to the axial tilt of the Earth...

 but it experiences many different climates, depending on altitude and weather. The islands receive most rainfall from the trade wind
Trade wind
The trade winds are the prevailing pattern of easterly surface winds found in the tropics, within the lower portion of the Earth's atmosphere, in the lower section of the troposphere near the Earth's equator...

s on their north and east flanks (the windward side) as a result of orographic precipitation. Coastal areas in general and especially the south and west flanks or leeward
Windward and leeward
Windward is the direction upwind from the point of reference. Leeward is the direction downwind from the point of reference. The side of a ship that is towards the leeward is its lee side. If the vessel is heeling under the pressure of the wind, this will be the "lower side"...

 sides, tend to be drier.

In general, the Hawaiian Islands receive most of their precipitation during the winter months (October to April). Drier conditions generally prevail from May to September, but the warmer temperatures increase the risk of hurricanes.

Temperatures at sea level generally range from highs of 85-90 °F (29-32 °C) during the summer months to 79-83 °F (26-28 °C) during the winter months. Rarely does the temperature rise above 90 °F (32 °C) or drop below 60 °F (16 °C) at lower elevations. Temperatures are lower at higher altitudes; in fact, the three highest mountains of Mauna Kea
Mauna Kea
Mauna Kea is a volcano on the island of Hawaii. Standing above sea level, its peak is the highest point in the state of Hawaii. However, much of the mountain is under water; when measured from its oceanic base, Mauna Kea is over tall—significantly taller than Mount Everest...

, Mauna Loa
Mauna Loa
Mauna Loa is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean, and the largest on Earth in terms of volume and area covered. It is an active shield volcano, with a volume estimated at approximately , although its peak is about lower than that...

, and Haleakala
Haleakala
Haleakalā , or the East Maui Volcano, is a massive shield volcano that forms more than 75% of the Hawaiian Island of Maui. The western 25% of the island is formed by the West Maui Mountains.- History :...

 often receive snowfall during the winter.

One distinctive feature of Hawaii’s climate is the small annual variation in temperature range. This is because there is only a slight variation in length of night and day from one part of Hawaii to another because all its islands lie within a narrow latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

 band. The small variations in the length of the daylight period, together with the smaller annual variations in the altitude of the sun above the horizon, result in relatively small variations in the amount of incoming solar energy from one time of the year to another. The surface waters of the open ocean around Hawaii range from 77 °F (25 °C) between late February and early April, to a maximum of 83 °F (28.3 °C) in late September or early October. With water temperatures this mild for hundreds of miles around, the air that reaches Hawaii is neither very hot nor very cold. Temperatures of 90 °F (32.2 °C) and above are quite uncommon (with the exception of dry, leeward areas). In the leeward areas, temperatures may reach into the low 90’s several days during the year, but temperatures higher than these are unusual. The highest temperature ever recorded on the islands was 100 °F on April 27, 1931 in Pahala.

The other reason for the small variation in air temperature is the nearly constant flow of fresh ocean air across the islands. Just as the temperature of the ocean surface varies comparatively little from season to season, so also does the temperature of air that has moved great distances across the ocean; the air brings with it to the land the mild temperature regime characteristic of the surrounding ocean. In the central North Pacific, the trade winds represent the outflow of air from the great region of high pressure, the North Pacific High
North Pacific High
The North Pacific High is a semi-permanent, subtropical anticyclone located in the north east of the Pacific Ocean north east of Hawaii. It is strongest during the northern hemisphere summer, and shifts towards the equator during the winter when the Aleutian Low becomes more active....

, typically located well north and east of the Hawaiian Islands. The Pacific High, and with it the trade-wind zone, moves north and south with changing angle of the sun, so that it reaches its northernmost position in the summer. This brings trade winds during the period of May through September, when they are prevalent 80 to 95 percent of the time. From October through April, the heart of the trade winds moves south of Hawaii; however, the winds still blow much of the time. They provide a system of natural year-long ventilation throughout the islands and bring mild temperatures characteristic of air that has moved great distances across tropical waters.

Winds


Island wind patterns are very complex. Though the trade winds are fairly constant, their relatively uniform air flow is distorted and disrupted by mountains, hills, and valleys. Usually winds blow upslope by day and downslope by night. Local conditions that produce occasional violent winds are not well understood. These are very localized, sometimes reaching speeds of 60 to 100 mph (96.6 to 160.9 km/h) and are best known in the settled areas of Kula and Lahaina on Maui. The Kula winds are strong downslope winds on the lower slopes of the west side of Haleakala. These winds tend to be strongest from 2000 to 4000 ft (609.6 to 1,219.2 m) above mean sea level. The Lahaina winds are also downslope winds, but are somewhat different. They are also called "lehua winds" after the ōhia lehua (Metrosideros polymorpha
Metrosideros polymorpha
The ōhia lehua is a species of flowering evergreen tree in the myrtle family, Myrtaceae, that is endemic to the six largest islands of Hawaii. It is a highly variable tree, being tall in favorable situations, and much smaller when growing in boggy soils or on basalt...

), whose red blossoms fill the air when these strong winds blow. They issue from canyons at the base of the western Maui mountains, where steeper canyon slopes meet the more gentle piedmont
Foothills
Foothills are geographically defined as gradual increases in elevation at the base of a mountain range. They are a transition zone between plains and low relief hills to the adjacent topographically high mountains.-Examples:...

 slope below. These winds only occur every 8 to 12 years. They are extremely violent, with wind speeds of 80 mi/h or more.

Cloud formation


Under trade wind conditions, there is very often a pronounced moisture discontinuity between 4000 and 8000 ft (1,219.2 and 2,438.4 m). Below these heights, the air is moist; above, it is dry. The break (a large-scale feature of the Pacific High) is caused by a temperature inversion embedded in the moving trade wind air. The inversion tends to suppress the vertical movement of air and so restricts cloud development to the zone just below the inversion. The inversion is present 50 to 70 percent of the time; its height fluctuates from day to day, but it is usually between 5000 and 7000 ft (1,524 and 2,133.6 m). On trade wind days when the inversion is well defined, the clouds develop below these heights with only an occasional cloud top breaking through the inversion. These towering clouds form along the mountains where the incoming trade wind air converges as it moves up a valley and is forced up and over the mountains to heights of several thousand feet. On days without an inversion, the sky is almost cloudless (completely cloudless skies are extremely rare). In leeward areas well screened from the trade winds (such as the west coast of Maui), skies are clear 30 to 60 percent of the time. Windward areas tend to be cloudier during the summer, when the trade winds and associated clouds are more prevalent, while leeward areas, which are less affected by cloudy conditions associated with trade wind cloudiness, tend to be cloudier during the winter, when storm fronts pass through more frequently. On Maui, the cloudiest zones are at and just below the summits of the mountains, and at elevations of 2000 to 4000 ft (609.6 to 1,219.2 m) on the windward sides of Haleakala. In these locations the sky is cloudy more than 70 percent of the time. The usual clarity of the air in the high mountains is associated with the low moisture content of the air.

Precipitation


Frequent light showers fall in Hawaii. On windward coasts, many brief showers are common, not one of which is heavy enough to produce more than 0.01 in (0.254 mm) of rain. The usual run of trade wind weather yields many light showers in the lowlands, whereas torrential rains are associated with a sudden surge in the trade winds or with a major storm. Hana has had as much as 28 in (711.2 mm) of rain in a single 24-hour period.

Major storms occur most frequently in October through March. There may be as many as six or seven major storm events in a year. Such storms bring heavy rains and can be accompanied by strong local winds. The storms may be associated with the passage of a cold front
Cold front
A cold front is defined as the leading edge of a cooler mass of air, replacing a warmer mass of air.-Development of cold front:The cooler and denser air wedges under the less-dense warmer air, lifting it...

 , the leading edge of a mass of relatively cool air that is moving from west to east or from northwest to southeast.

Kona storm
Kona storm
Kona storms are a type of seasonal cyclone in the Hawaiian Islands, usually formed in the winter from winds coming from the westerly "kona" direction. They are mainly cold core cyclones, which places them in the extratropical cyclone rather than the subtropical cyclone category...

s are features of the winter season. The name come from winds out of the "kona" or usually leeward direction. Rainfall in a well-developed Kona storm is widespread and more prolonged than in the usual cold-front storm. Kona storm rains are usually most intense in an arc, extending from south to east of the storm and well in advance of its center. Kona rains last from several hours to several days. The rains may continue steadily, but the longer lasting ones are characteristically interrupted by intervals of lighter rain or partial clearing, as well as by intense showers superimposed on the more moderate continuous, steady rain. An entire winter may pass without a single well-developed Kona storm. More often there are one or two such storms a year; sometimes four or five.
Three harbors provide some protection from Kona storms: Kahului Harbor (used mostly for commercial vessels), Lahaina and Maalaea Harbors (used primarily) for sailing craft.

Hurricanes



The hurricane season in the Hawaiian Islands is roughly from June through November, when hurricanes and tropical storms are most probable in the North Pacific. These storms tend to originate off the coast of Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 (particularly the Baja California peninsula
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...

) and track west or northwest towards the islands.

True hurricanes are very rare in Hawaii; only four have affected the islands during 63 years. Tropical storms are more frequent. These have more modest winds, below 74 mph (119.1 km/h). Because tropical storms resemble Kona storms, and because early records do not distinguish clearly between them, it has been difficult to estimate the average frequency of tropical storms. Every year or two a tropical storm will affect the weather in some part of the islands. Unlike cold front
Cold front
A cold front is defined as the leading edge of a cooler mass of air, replacing a warmer mass of air.-Development of cold front:The cooler and denser air wedges under the less-dense warmer air, lifting it...

s and Kona storms, hurricanes and tropical storms are most likely to occur during the last half of the year, from July through December.

As storms cross the Pacific, they tend to lose strength if they bear northward and encounter cooler water. The topography of the highest islands (Haleakalā on Maui, Mauna Kea and Mauna Loa on the Big Island) may protect these islands, because Kauai has been hit more often in the last 50 years than the others.

Effect on trade winds



Despite being a tiny speck within the vast Pacific Ocean, the Hawaiian Islands have a surprising effect on ocean currents and circulation patterns over much of the Pacific. In the Northern Hemisphere, trade winds blow from northeast to southwest, from North and South America toward Asia, between the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....

 and 30 degrees north
30th parallel north
The 30th parallel north is a circle of latitude that is 30 degrees north of the Earth's equatorial plane. It stands one-third of the way between the equator and the North Pole and crosses Africa, Asia, the Pacific Ocean, North America and the Atlantic Ocean....

 latitude. Typically, the trade winds continue across the Pacific — unless something gets in their way, like an island.

Hawaii's high mountains present a substantial obstacle to the trade winds. The elevated topography blocks the airflow, effectively splitting the trade winds in two. This split causes a zone of weak winds, called a "wind wake
Wake
A wake is the region of recirculating flow immediately behind a moving or stationary solid body, caused by the flow of surrounding fluid around the body.-Fluid dynamics:...

", on the leeward side of the islands.

Aerodynamic theory
Aerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...

 indicates that an island wind wake effect should dissipate within a few hundred kilometers and not be felt in the western Pacific. However, the wind wake caused by the Hawaiian Islands extends 1860 miles (2,993.4 km), roughly 10 times longer than any other wake. The long wake testifies to the strong interaction between the atmosphere and ocean, which has strong implications for global climate research. It is also important for understanding natural climate variations, like El Niño.

There are number of reasons why this has only been observed in Hawaii. First, the ocean reacts slowly to fast-changing winds; winds must be steady to exert force on the ocean, such as the trade winds. Second, the high mountain topography provides a significant disturbance to the winds. Third, the Hawaiian Islands are large in horizontal scale, extending over four degrees in latitude. It is this active interaction between wind, ocean current, and temperature that creates this uniquely long wake west of Hawaii.

The wind wake drives an eastward "counter current" that brings warm water 5000 miles (8,046.7 km) from the Asian coast. This warm water drives further changes in wind, allowing the island effect to extend far into the western Pacific. The counter current had been observed by oceanographer
Oceanography
Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean...

s near the Hawaiian Islands years before the long wake was discovered, but they did not know what caused it.

Further reading