Loihi Seamount
Encyclopedia
Lōihi Seamount is an active undersea volcano
located around 35 km (22 mi) off the southeast coast of the island of Hawaii
about 975 m (3,198.8 ft) below sea level
. It lies on the flank of Mauna Loa
, the largest shield volcano
on Earth. Lōihi means "long" in Hawaiian.
Lōihi Seamount is the newest volcano in the Hawaiian-Emperor seamount chain
, a string of volcanoes that stretches over 5800 km (3,604 mi) northwest of Lōihi and the island of Hawaii. Unlike most active volcanoes in the Pacific Ocean
that make up the active plate margins
on the Pacific Ring of Fire
, Lōihi and the other volcanoes of the Hawaiian-Emperor seamount chain are hotspot volcanoes
and formed well away from the nearest plate boundary. Volcanoes in the Hawaiian Islands arise from the Hawaii hotspot
, and as the youngest volcano in the chain, Lōihi is the only Hawaiian volcano in the deep submarine preshield stage of development.
Lōihi began forming around 400,000 years ago and is expected to begin emerging above sea level about 10,000–100,000 years from now. At its summit, Lōihi Seamount stands more than 3000 m (9,842.5 ft) above the seafloor, making it taller than Mount St. Helens
was before its catastrophic 1980 eruption
. The summit is currently 975 m (3,198.8 ft) below sea level. A diverse microbial community resides around Lōihi's many hydrothermal vent
s.
In the summer of 1996, a swarm
of 4,070 earthquake
s was recorded at Lōihi. This series included more earthquakes than any other swarm in Hawaiian recorded history. The swarm altered 10 to 13 km² (3.9 to 5 sqmi) of the seamount's summit; one section, Pele's Vents, collapsed entirely upon itself and formed the renamed Pele's Pit. The volcano has remained relatively active since the 1996 swarm and is monitored by the National Oceanic and Atmospheric Administration
(NOAA) and the United States Geological Survey
(USGS). The Hawaii Undersea Geological Observatory (HUGO) provided real-time data on Lōihi between 1997 and 2002. Lōihi last erupted in 1996, before a summer earthquake swarm.
, or underwater volcano, on the flank of Mauna Loa
, the Earth's largest shield volcano
. It is the newest volcano created by the Hawaii hotspot
in the extensive Hawaiian-Emperor seamount chain
. The distance between the summit of the older Mauna Loa and the summit of Lōihi is about 80 km (49.7 mi), which is, coincidentally, also the approximate diameter of the Hawaii hotspot
. Lōihi consists of a summit area with three pit crater
s, an 11 km (7 mi) long rift zone
extending north from the summit, and a 19 km (12 mi) long rift zone extending south-southeast from the summit.
The summit's pit crater
s are named West Pit, East Pit, and Pele's Pit. Pele's Pit is the youngest of this group and is located at the southern part of the summit. The walls of Pele's Pit stand 200 m (656.2 ft) high and were formed in July 1996 when its predecessor, Pele's Vent, a hydrothermal field near Lōihi's summit, collapsed into a large depression
. The thick crater walls of Pele's Pit—averaging 20 m (65.6 ft) in width, unusually thick for Hawaiian volcanic craters—suggest its craters have filled with lava multiple times in the past.
Lōihi's north–south trending rift zones create a distinctive elongated shape, from which the volcano's Hawaiian name, meaning "long", derives. The north rift zone consists of a longer western portion and a shorter eastern rift zone. Observations show that both the north and south rift zones lack sediment cover, indicating recent activity. A bulge in the western part of the north rift zone contains three 60–80 m (196.9–262.5 ft) cone-shaped prominences.
Until 1970, Lōihi was thought to be an inactive volcano that had been transported to its current location by sea-floor spreading. The seafloor under Hawaii is years old and was created at the East Pacific Rise
, an oceanic spreading center
where new sea floor forms from magma that erupts from the mantle. New oceanic crust
moves away from the spreading center. Over a period of years, the sea floor under Hawaii moved from the East Pacific Rise to its present location 6000 km (3,728.2 mi) west, carrying ancient seamounts with it. When scientists investigated a series of earthquakes off Hawaii in 1970, they discovered that Lōihi was an active member of the Hawaiian-Emperor seamount chain. The age pattern of Lōihi's summit craters confirms that volcanism at Lōihi has slowly been moving east as Lōihi moves away from its origins over the Hawaii hotspot.
Lōihi rises more than 3000 m (9,842.5 ft) from the ocean floor, but its peak is still 975 m (3,199 ft) below the ocean surface. Lōihi is built on the seafloor with a slope of about five degrees. Its northern base on the flank of Mauna Loa is 1900 m (6,233.6 ft) below sea level, but its southern base is a more substantial 4755 m (15,600.4 ft) below the surface. Thus, the summit is 931 m (3,054 ft) above the seafloor as measured from the base of its north flank, but 3786 m (12,421 ft) high when measured from the base of its southern flank.
Lōihi is following the pattern of development
that is characteristic of all Hawaiian volcanoes. Geochemical evidence from Lōihi lavas indicates that Lōihi is in transition between the preshield and shield volcano stage, providing valuable clues to the early development of Hawaiian volcanoes. In the preshield stage, Hawaiian volcanoes have steeper sides and a lower level of activity, producing an alkali
basalt
lava. Continued volcanism is expected to eventually create an island at Lōihi. Lōihi experiences frequent landslides; the growth of the volcano has destabilized its slopes, and extensive areas of debris inhabit the steep southeastern face. Similar deposits from other Hawaiian volcanoes indicate that landslide debris is an important product of Hawaiian volcanos' early development. Lōihi is predicted to rise above the surface in 10,000 to 100,000 years.
was used to determine the age of rock samples from Lōihi. The Hawaii Center for Volcanology tested samples recovered by various expeditions, notably the 1978 expedition, which provided 17 dredge samples. Most of the samples were found to be of ancient origin; the oldest dated rock is around 300,000 years old. Following the 1996 event, some young breccia
was also collected. Based on the samples, scientists estimate Lōihi is about 400,000 years old. The rock accumulates at an average rate of 3.5 mm (0.137795275590551 in) per year near the base, and 7.8 mm (0.307086614173228 in) near the summit. If the data model from other volcanoes such as Kīlauea
holds true for Lōihi, 40% of the volcano's mass formed within the last 100,000 years. Assuming a linear growth rate, Lōihi is 250,000 years old. However, as with all hotspot volcanoes, Lōihi's level of activity has increased with time; therefore, it would take at least 400,000 years for such a volcano to reach Lōihi's mass. As Hawaiian volcanoes drift northwest at a rate of about 10 cm (4 in) a year, Lōihi was 40 km (25 mi) southeast of its current position at the time of its initial eruption.
. In the past few decades, several earthquake swarm
s have been attributed to Lōihi, the largest of which are summarized in the table below. The volcano's activity is now known to predate scientific record keeping of its activity, which commenced in 1959. Most earthquake swarms at Lōihi have lasted less than two days; the two exceptions are the 1991–92 earthquake, lasting several months, and the 1996 event, which was shorter but much more pronounced. Both of the earthquakes followed a pattern of activity that began on the flank and migrated to the summit. The 1996 event was directly observed by an autonomous ocean bottom observatory (OBO), allowing scientists to calculate the depth of the earthquakes as 6 km (4 mi) to 8 km (5 mi) below the summit, approximating to the position of Lōihi's extremely shallow magma chamber
. This is evidence that Lōihi's seismicity is volcanic in origin.
The low-level seismic activity documented on Lōihi since 1959 has shown that between two and ten earthquakes per month are traceable to the summit. Earthquake swarm data have been used to analyze how well Lōihi's rocks propagate seismic wave
s and to investigate the relationship between earthquakes and eruptions. This low level activity is periodically punctuated by large swarms of earthquakes, each swarm comprising up to hundreds of earthquakes. The majority of the earthquakes are not distributed close to the summit, though they follow a north–south trend. Rather, most of the earthquakes occur in the southwest portion of Lōihi. The largest recorded swarms took place on Lōihi in 1971, 1972, 1975, 1991–92 and 1996. The nearest seismic station is around 30 km (18.6 mi) from Lōihi, on the south coast of Hawaii
. Seismic events that have a magnitude
under 2 are recorded often, but their location cannot be determined precisely as it can for larger events. In fact, HUGO (Hawaii Undersea Geological Observatory), positioned on Lōihi's flank, detected ten times as many earthquakes as were recorded by the Hawaiian Volcano Observatory
(HVO) seismic network.
The largest amount of activity recorded for the Lōihi seamount was a swarm
of 4,070 earthquakes between July 16 and August 9, 1996. This series of earthquakes was the largest recorded for any Hawaiian volcano to date in both amount and intensity. Most of the earthquakes had moment magnitudes
of less than 3.0. "Several hundred" had a magnitude greater than 3.0, including more than 40 greater than 4.0 and a 5.0 tremor.
The final two weeks of the earthquake swarm were observed by a quick response cruise launched in August 1996. The National Science Foundation
funded an expedition by University of Hawaii
scientists, led by Frederick Duennebier, that began investigating the swarm and its origin in August 1996. The scientists' assessment laid the groundwork for many of the expeditions that followed. Follow-up expeditions to Lōihi took place, including a series of manned-submersible
dives in August and September.
These were supplemented by a great deal of shore-based research. Fresh rock collected during the expedition revealed that an eruption occurred before the earthquake swarm.
Submersible dives in August were followed by NOAA-funded research in September and October 1996. These more detailed studies showed the southern portion of Lōihi's summit had collapsed, a result of a swarm of earthquakes and the rapid withdrawal of magma from the volcano. A crater 1 km (0.621372736649807 mi) across and 300 m (984.3 ft) deep formed out of the rubble. The event involved the movement of cubic meters of volcanic material. A region of 10 to 13 km2 (4 to 5 sq mi) of the summit was altered and populated by bus-sized pillow lava blocks, precariously perched along the outer rim of the newly formed crater. "Pele's Vents," an area on the southern side, previously considered stable, collapsed completely into a giant pit, renamed "Pele's Pit". Seawater flowed into the newborn pit on the northern end of the volcano, mixing with loose minerals and bacterial matter before flowing over Lōihi's western edge. The resulting strong current made submersible diving hazardous in the region.
The researchers were continually met by clouds of sulfide
and sulfate
. The sudden collapse of Pele's Vents caused a large discharge of hydrothermal material. The presence of certain indicator minerals in the mixture suggested temperatures exceeded 250 °C, a record for an underwater volcano. The composition of the materials was similar to that of black smokers, the hydrothermal vent plumes located along mid-ocean ridge
s. Samples from mounds built by discharges from the hydrothermal plumes resembled white smokers.
The studies demonstrated that the most volcanically and hydrothermally active area was along the southern rift. Dives on the less active northern rim indicated that the terrain was more stable there, and high lava columns
were still standing upright. A new hydrothermal vent field (Naha Vents) was located in the upper-south rift zone, at a depth of 1325 m (4,347.1 ft).
5.1 and 5.4, on May 13 and July 17. Both originated from a depth of 44 km (27.3 mi). On April 23, a magnitude 4.3 earthquake was recorded at a depth of approximately 33 km (20.5 mi). Between December 7, 2005, and January 18, 2006, a swarm of around 100 earthquakes occurred, the largest measuring 4 on the Moment magnitude scale
and 12 km (7 mi) to 28 km (17 mi) deep. Another earthquake measuring 4.7 was later recorded approximately midway between Lōihi and Pāhala (on the south coast of the island of Hawaii
).
| FeMO (Fe-Oxidizing Microbial Observatory) cruises to investigate iron-oxidizing microbes at Lōihi.
Much is learned about Lōihi's microbial community.
|}
Submarine volcano
Submarine volcanoes are underwater fissures in the Earth's surface from which magma can erupt. They are estimated to account for 75% of annual magma output. The vast majority are located near areas of tectonic plate movement, known as ocean ridges...
located around 35 km (22 mi) off the southeast 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...
about 975 m (3,198.8 ft) below sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
. It lies on the flank of 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...
, 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 Earth. Lōihi means "long" in Hawaiian.
Lōihi Seamount is the newest volcano in 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...
, a string of volcanoes that stretches over 5800 km (3,604 mi) northwest of Lōihi and the island of Hawaii. Unlike most active volcanoes in the 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...
that make up the active plate margins
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
on the Pacific Ring of Fire
Pacific Ring of Fire
The Pacific Ring of Fire is an area where large numbers of earthquakes and volcanic eruptions occur in the basin of the Pacific Ocean. In a horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and/or plate movements...
, Lōihi and the other volcanoes of the Hawaiian-Emperor seamount chain are hotspot volcanoes
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...
and formed well away from the nearest plate boundary. Volcanoes in the Hawaiian Islands arise from the Hawaii hotspot
Hawaii hotspot
The Hawaii hotspot is the volcanic hotspot that created the Hawaiian Islands in the central Pacific Ocean, and is one of Earth's best-known and most heavily-studied hotspots....
, and as the youngest volcano in the chain, Lōihi is the only Hawaiian volcano in the deep submarine preshield stage of development.
Lōihi began forming around 400,000 years ago and is expected to begin emerging above sea level about 10,000–100,000 years from now. At its summit, Lōihi Seamount stands more than 3000 m (9,842.5 ft) above the seafloor, making it taller than Mount St. Helens
Mount St. Helens
Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is south of Seattle, Washington and northeast of Portland, Oregon. Mount St. Helens takes its English name from the British diplomat Lord St Helens, a...
was before its catastrophic 1980 eruption
1980 eruption of Mount St. Helens
The 1980 eruption of Mount St. Helens, a stratovolcano located in Washington state, in the United States, was a major volcanic eruption. The eruption was the only significant one to occur in the contiguous 48 U.S. states since the 1915 eruption of Lassen Peak in California...
. The summit is currently 975 m (3,198.8 ft) below sea level. A diverse microbial community resides around Lōihi's many hydrothermal vent
Hydrothermal vent
A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both...
s.
In the summer of 1996, a swarm
Earthquake swarm
Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but the United States Geological Survey points out that an event may be on the order of days, weeks, or...
of 4,070 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 was recorded at Lōihi. This series included more earthquakes than any other swarm in Hawaiian recorded history. The swarm altered 10 to 13 km² (3.9 to 5 sqmi) of the seamount's summit; one section, Pele's Vents, collapsed entirely upon itself and formed the renamed Pele's Pit. The volcano has remained relatively active since the 1996 swarm and is monitored by the National Oceanic and Atmospheric Administration
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
(NOAA) and the United States Geological Survey
United States Geological Survey
The United States 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, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...
(USGS). The Hawaii Undersea Geological Observatory (HUGO) provided real-time data on Lōihi between 1997 and 2002. Lōihi last erupted in 1996, before a summer earthquake swarm.
Geology
Lōihi is a seamountSeamount
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...
, or underwater volcano, on the flank of 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...
, the Earth's 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...
. It is the newest volcano created by the Hawaii hotspot
Hawaii hotspot
The Hawaii hotspot is the volcanic hotspot that created the Hawaiian Islands in the central Pacific Ocean, and is one of Earth's best-known and most heavily-studied hotspots....
in the extensive 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...
. The distance between the summit of the older Mauna Loa and the summit of Lōihi is about 80 km (49.7 mi), which is, coincidentally, also the approximate diameter of the Hawaii 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...
. Lōihi consists of a summit area with three pit crater
Pit crater
A pit crater is a depression formed by a sinking of the ground surface lying above a void or empty chamber, rather than by the eruption of a volcano or lava vent. It is often found in chains or troughs. Several craters may merge into a linear alignment...
s, an 11 km (7 mi) long rift zone
Rift zone
A rift zone is a feature of some volcanoes, especially the shield volcanoes of Hawaii, in which a linear series of fissures in the volcanic edifice allows lava to be erupted from the volcano's flank instead of from its summit...
extending north from the summit, and a 19 km (12 mi) long rift zone extending south-southeast from the summit.
The summit's pit crater
Pit crater
A pit crater is a depression formed by a sinking of the ground surface lying above a void or empty chamber, rather than by the eruption of a volcano or lava vent. It is often found in chains or troughs. Several craters may merge into a linear alignment...
s are named West Pit, East Pit, and Pele's Pit. Pele's Pit is the youngest of this group and is located at the southern part of the summit. The walls of Pele's Pit stand 200 m (656.2 ft) high and were formed in July 1996 when its predecessor, Pele's Vent, a hydrothermal field near Lōihi's summit, collapsed into a large depression
Depression (geology)
A depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms.Structural or tectonic related:...
. The thick crater walls of Pele's Pit—averaging 20 m (65.6 ft) in width, unusually thick for Hawaiian volcanic craters—suggest its craters have filled with lava multiple times in the past.
Until 1970, Lōihi was thought to be an inactive volcano that had been transported to its current location by sea-floor spreading. The seafloor under Hawaii is years old and was created at the East Pacific Rise
East Pacific Rise
The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate...
, an oceanic spreading center
Mid-ocean ridge
A mid-ocean ridge is a general term for an underwater mountain system that consists of various mountain ranges , typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading...
where new sea floor forms from magma that erupts from the mantle. New oceanic crust
Oceanic crust
Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium...
moves away from the spreading center. Over a period of years, the sea floor under Hawaii moved from the East Pacific Rise to its present location 6000 km (3,728.2 mi) west, carrying ancient seamounts with it. When scientists investigated a series of earthquakes off Hawaii in 1970, they discovered that Lōihi was an active member of the Hawaiian-Emperor seamount chain. The age pattern of Lōihi's summit craters confirms that volcanism at Lōihi has slowly been moving east as Lōihi moves away from its origins over the Hawaii hotspot.
Lōihi rises more than 3000 m (9,842.5 ft) from the ocean floor, but its peak is still 975 m (3,199 ft) below the ocean surface. Lōihi is built on the seafloor with a slope of about five degrees. Its northern base on the flank of Mauna Loa is 1900 m (6,233.6 ft) below sea level, but its southern base is a more substantial 4755 m (15,600.4 ft) below the surface. Thus, the summit is 931 m (3,054 ft) above the seafloor as measured from the base of its north flank, but 3786 m (12,421 ft) high when measured from the base of its southern flank.
Lōihi is following the pattern of development
Evolution of Hawaiian volcanoes
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 across the North Pacific Ocean, called the Hawaiian-Emperor seamount chain....
that is characteristic of all Hawaiian volcanoes. Geochemical evidence from Lōihi lavas indicates that Lōihi is in transition between the preshield and shield volcano stage, providing valuable clues to the early development of Hawaiian volcanoes. In the preshield stage, Hawaiian volcanoes have steeper sides and a lower level of activity, producing an alkali
Alkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
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...
lava. Continued volcanism is expected to eventually create an island at Lōihi. Lōihi experiences frequent landslides; the growth of the volcano has destabilized its slopes, and extensive areas of debris inhabit the steep southeastern face. Similar deposits from other Hawaiian volcanoes indicate that landslide debris is an important product of Hawaiian volcanos' early development. Lōihi is predicted to rise above the surface in 10,000 to 100,000 years.
Age and growth
Radiometric datingRadiometric dating
Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates...
was used to determine the age of rock samples from Lōihi. The Hawaii Center for Volcanology tested samples recovered by various expeditions, notably the 1978 expedition, which provided 17 dredge samples. Most of the samples were found to be of ancient origin; the oldest dated rock is around 300,000 years old. Following the 1996 event, some young breccia
Breccia
Breccia is a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix, that can be either similar to or different from the composition of the fragments....
was also collected. Based on the samples, scientists estimate Lōihi is about 400,000 years old. The rock accumulates at an average rate of 3.5 mm (0.137795275590551 in) per year near the base, and 7.8 mm (0.307086614173228 in) near the summit. If the data model from other volcanoes such as Kīlauea
Kilauea
Kīlauea is a volcano in the Hawaiian Islands, and one of five shield volcanoes that together form the island of Hawaii. Kīlauea means "spewing" or "much spreading" in the Hawaiian language, referring to its frequent outpouring of lava. The Puu Ōō cone has been continuously erupting in the eastern...
holds true for Lōihi, 40% of the volcano's mass formed within the last 100,000 years. Assuming a linear growth rate, Lōihi is 250,000 years old. However, as with all hotspot volcanoes, Lōihi's level of activity has increased with time; therefore, it would take at least 400,000 years for such a volcano to reach Lōihi's mass. As Hawaiian volcanoes drift northwest at a rate of about 10 cm (4 in) a year, Lōihi was 40 km (25 mi) southeast of its current position at the time of its initial eruption.
Activity
Lōihi is a young and fairly active volcano, although less so than nearby KīlaueaKilauea
Kīlauea is a volcano in the Hawaiian Islands, and one of five shield volcanoes that together form the island of Hawaii. Kīlauea means "spewing" or "much spreading" in the Hawaiian language, referring to its frequent outpouring of lava. The Puu Ōō cone has been continuously erupting in the eastern...
. In the past few decades, several earthquake swarm
Earthquake swarm
Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but the United States Geological Survey points out that an event may be on the order of days, weeks, or...
s have been attributed to Lōihi, the largest of which are summarized in the table below. The volcano's activity is now known to predate scientific record keeping of its activity, which commenced in 1959. Most earthquake swarms at Lōihi have lasted less than two days; the two exceptions are the 1991–92 earthquake, lasting several months, and the 1996 event, which was shorter but much more pronounced. Both of the earthquakes followed a pattern of activity that began on the flank and migrated to the summit. The 1996 event was directly observed by an autonomous ocean bottom observatory (OBO), allowing scientists to calculate the depth of the earthquakes as 6 km (4 mi) to 8 km (5 mi) below the summit, approximating to the position of Lōihi's extremely shallow magma chamber
Magma chamber
A magma chamber is a large underground pool of molten rock found beneath the surface of the Earth. The molten rock in such a chamber is under great pressure, and given enough time, that pressure can gradually fracture the rock around it creating outlets for the magma...
. This is evidence that Lōihi's seismicity is volcanic in origin.
The low-level seismic activity documented on Lōihi since 1959 has shown that between two and ten earthquakes per month are traceable to the summit. Earthquake swarm data have been used to analyze how well Lōihi's rocks propagate seismic wave
Seismic wave
Seismic waves are waves of energy that travel through the earth, and are a result of an earthquake, explosion, or a volcano that imparts low-frequency acoustic energy. Many other natural and anthropogenic sources create low amplitude waves commonly referred to as ambient vibrations. Seismic waves...
s and to investigate the relationship between earthquakes and eruptions. This low level activity is periodically punctuated by large swarms of earthquakes, each swarm comprising up to hundreds of earthquakes. The majority of the earthquakes are not distributed close to the summit, though they follow a north–south trend. Rather, most of the earthquakes occur in the southwest portion of Lōihi. The largest recorded swarms took place on Lōihi in 1971, 1972, 1975, 1991–92 and 1996. The nearest seismic station is around 30 km (18.6 mi) from Lōihi, on the south coast 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...
. Seismic events that have a magnitude
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
under 2 are recorded often, but their location cannot be determined precisely as it can for larger events. In fact, HUGO (Hawaii Undersea Geological Observatory), positioned on Lōihi's flank, detected ten times as many earthquakes as were recorded 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...
(HVO) seismic network.
1996 earthquake swarm
| Major Events |
This table indexes only possible volcanic eruptions and major events. Lōihi has also been the site of multiple earthquake swarms occurring on a nearly semi-annual basis. |
|---|
The largest amount of activity recorded for the Lōihi seamount was a swarm
Earthquake swarm
Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but the United States Geological Survey points out that an event may be on the order of days, weeks, or...
of 4,070 earthquakes between July 16 and August 9, 1996. This series of earthquakes was the largest recorded for any Hawaiian volcano to date in both amount and intensity. Most of the earthquakes had moment magnitudes
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
of less than 3.0. "Several hundred" had a magnitude greater than 3.0, including more than 40 greater than 4.0 and a 5.0 tremor.
The final two weeks of the earthquake swarm were observed by a quick response cruise launched in August 1996. The National Science Foundation
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...
funded an expedition by University of Hawaii
University of Hawaii
The University of Hawaii System, formally the University of Hawaii and popularly known as UH, is a public, co-educational college and university system that confers associate, bachelor, master, and doctoral degrees through three university campuses, seven community college campuses, an employment...
scientists, led by Frederick Duennebier, that began investigating the swarm and its origin in August 1996. The scientists' assessment laid the groundwork for many of the expeditions that followed. Follow-up expeditions to Lōihi took place, including a series of manned-submersible
Submersible
A submersible is a small vehicle designed to operate underwater. The term submersible is often used to differentiate from other underwater vehicles known as submarines, in that a submarine is a fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersible is...
dives in August and September.
These were supplemented by a great deal of shore-based research. Fresh rock collected during the expedition revealed that an eruption occurred before the earthquake swarm.
Submersible dives in August were followed by NOAA-funded research in September and October 1996. These more detailed studies showed the southern portion of Lōihi's summit had collapsed, a result of a swarm of earthquakes and the rapid withdrawal of magma from the volcano. A crater 1 km (0.621372736649807 mi) across and 300 m (984.3 ft) deep formed out of the rubble. The event involved the movement of cubic meters of volcanic material. A region of 10 to 13 km2 (4 to 5 sq mi) of the summit was altered and populated by bus-sized pillow lava blocks, precariously perched along the outer rim of the newly formed crater. "Pele's Vents," an area on the southern side, previously considered stable, collapsed completely into a giant pit, renamed "Pele's Pit". Seawater flowed into the newborn pit on the northern end of the volcano, mixing with loose minerals and bacterial matter before flowing over Lōihi's western edge. The resulting strong current made submersible diving hazardous in the region.
The researchers were continually met by clouds of sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
and sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
. The sudden collapse of Pele's Vents caused a large discharge of hydrothermal material. The presence of certain indicator minerals in the mixture suggested temperatures exceeded 250 °C, a record for an underwater volcano. The composition of the materials was similar to that of black smokers, the hydrothermal vent plumes located along mid-ocean ridge
Mid-ocean ridge
A mid-ocean ridge is a general term for an underwater mountain system that consists of various mountain ranges , typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading...
s. Samples from mounds built by discharges from the hydrothermal plumes resembled white smokers.
The studies demonstrated that the most volcanically and hydrothermally active area was along the southern rift. Dives on the less active northern rim indicated that the terrain was more stable there, and high lava columns
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
were still standing upright. A new hydrothermal vent field (Naha Vents) was located in the upper-south rift zone, at a depth of 1325 m (4,347.1 ft).
Recent activity
Lōihi has remained largely quiet since the 1996 event; no activity was recorded from 2002 to 2004. The seamount showed signs of life again in 2005 by generating an earthquake bigger than any previously recorded there. USGS-ANSS (Advanced National Seismic System) reported two earthquakes, magnitudesMoment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
5.1 and 5.4, on May 13 and July 17. Both originated from a depth of 44 km (27.3 mi). On April 23, a magnitude 4.3 earthquake was recorded at a depth of approximately 33 km (20.5 mi). Between December 7, 2005, and January 18, 2006, a swarm of around 100 earthquakes occurred, the largest measuring 4 on the Moment magnitude scale
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
and 12 km (7 mi) to 28 km (17 mi) deep. Another earthquake measuring 4.7 was later recorded approximately midway between Lōihi and Pāhala (on the south 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...
).
Early work
October 2009| FeMO (Fe-Oxidizing Microbial Observatory) cruises to investigate iron-oxidizing microbes at Lōihi.
Much is learned about Lōihi's microbial community.
|}
Lōihi Seamount's first depiction on a map was on Survey Chart 4115, a bathymetric rendering of part of Hawaii compiled by the US Coast and Geodetic Survey in 1940. At the time, the seamount was non-notable, being one of many in the region. A large earthquake swarm first brought attention to it in 1952. That same year, geologist Gordon A. Macdonald hypothesized that the seamount was actually an active submarine 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...
, similar to the two active Hawaiian 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...
and Kīlauea
Kilauea
Kīlauea is a volcano in the Hawaiian Islands, and one of five shield volcanoes that together form the island of Hawaii. Kīlauea means "spewing" or "much spreading" in the Hawaiian language, referring to its frequent outpouring of lava. The Puu Ōō cone has been continuously erupting in the eastern...
. Macdonald's hypothesis placed the seamount as the newest volcano in 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...
, created by the Hawaii hotspot
Hawaii hotspot
The Hawaii hotspot is the volcanic hotspot that created the Hawaiian Islands in the central Pacific Ocean, and is one of Earth's best-known and most heavily-studied hotspots....
. However, because the earthquakes were oriented east–west (the direction of the volcanic fault) and there was no volcanic tremor
Harmonic tremor
Harmonic tremor describes a long-duration release of seismic energy, with distinct spectral lines, that often precedes or accompanies a volcanic eruption...
in seismometer
Seismometer
Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources...
s distant from the seamount, Macdonald attributed the earthquake to faulting rather than a volcanic eruption.
Geologists suspected the seamount could be an active undersea volcano, but without evidence the idea remained speculative. The volcano was largely ignored after the 1952 event, and was often mislabeled as an "older volcanic feature" in subsequent charts. Geologist Kenneth O. Emery is credited with naming the seamount in 1955, describing the long and narrow shape of the volcano as Lōihi, the Hawaiian
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...
word for "long". In 1978, an expedition studied intense, repeated seismic activity known as earthquake swarm
Earthquake swarm
Earthquake swarms are events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but the United States Geological Survey points out that an event may be on the order of days, weeks, or...
s in and around the Lōihi area. Rather than finding an old, extinct seamount, data collected revealed Lōihi to be a young, possibly active volcano. Observations showed volcano to be encrusted with young and old lava flows as well as actively venting hydrothermal fluids.
In 1978, a US Geological Survey research ship collected dredge
Dredge
Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location...
samples and photographed Lōihi's summit with the goal of studying whether Lōihi is active. Analysis of the photos and testing of pillow lava
Pillow lava
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion. Pillow lavas in volcanic rock are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one metre in...
rock samples appeared to show that the material was "fresh", yielding more evidence that Lōihi is still active. An expedition from October 1980 to January 1981 collected further dredge samples and photographs, providing additional confirmation. Studies indicated that the eruptions came from the southern part of the rift crater. This area is closest to the Hawaii hotspot, which supplies Lōihi with 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...
. Following a 1986 seismic event, a network of five ocean bottom observatories (OBOs) were deployed on Lōihi for a month. Lōihi's frequent seismicity makes it an ideal candidate for seismic study through OBOs. In 1987, the submersible
Submersible
A submersible is a small vehicle designed to operate underwater. The term submersible is often used to differentiate from other underwater vehicles known as submarines, in that a submarine is a fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersible is...
DSV Alvin
DSV Alvin
Alvin is a manned deep-ocean research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts. The vehicle was built by General Mills' Electronics Group in the same factory used to manufacture breakfast cereal-producing...
was used to survey
Traverse (surveying)
Traverse is a method in the field of surveying to establish control networks. It is also used in geodesy. Traverse networks involve placing survey stations along a line or path of travel, and then using the previously surveyed points as a base for observing the next point...
Lōihi.
Another autonomous observatory was positioned on Lōihi in 1991 to track earthquake swarms.
1996 to present
The bulk of information about Lōihi comes from dives made in response to the 1996 eruption. In a dive conducted almost immediately after seismic activity was reported, visibility was greatly reduced by high concentrations of displaced minerals and large floating mats of bacteria in the water. The bacteria that feed on the dissolved nutrients had already begun colonizing the new hydrothermal vents at Pele's Pit (formed from the collapse of the old ones), and may be indicators of the kinds of material ejected from the newly formed vents. They were carefully sampled for further analysis in a laboratory. An OBO briefly sat on the summit before a more permanent probe could be installed.Repeated multibeam bathymetric mapping was used to measure the changes in the summit following the 1996 collapse. Hydrothermal plume
Hydrothermal vent
A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both...
surveys confirmed changes in the energy, and dissolved minerals emanating from Lōihi. Hawaii Undersea Research Laboratory
Hawaii Undersea Research Laboratory
The Hawaii Undersea Research Laboratory is a regional undersea research facility under the auspices of the U. S. government's National Oceanic and Atmospheric Administration National Undersea Research Program and administered by the University of Hawaii. Its headquarters are at University of...
, HURL's 2000 m (6,562 ft) submersible Pisces V allowed scientists to sample the vent waters, microorganisms and hydrothermal mineral deposits.
In 1997, scientists from the University of Hawaii
University of Hawaii
The University of Hawaii System, formally the University of Hawaii and popularly known as UH, is a public, co-educational college and university system that confers associate, bachelor, master, and doctoral degrees through three university campuses, seven community college campuses, an employment...
installed an ocean bottom observatory (OBO) on the summit of Lōihi Seamount. The submarine observatory was nicknamed HUGO, (Hawaii Undersea Geological Observatory). HUGO was connected to the shore, 34 km (21.1 mi) away, by a fiber optic cable. It gave scientists real-time seismic, chemical and visual data about the state of Lōihi, which had by then become an international laboratory for the study of undersea volcanism. The cable that provided HUGO with power and communications broke in October 1998, effectively shutting it down. On January 19 of the following year, HUGO was visited by Pisces V. The observatory functioned for four years before it went dead again in 2002.
Since 2006, the Fe-Oxidizing Microbial Observatory (FeMO), funded by the National Science Foundation
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...
and Microbial Observatory Program, has led cruises to Lōihi investigate its microbiology
Microbiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...
every October. The first cruise, on the ship R/V Melville and exploiting the submersible JASON2, lasted from September 22 to October 9. These cruises study the large number of Fe-oxidizing bacteria
Chemotroph
Chemotrophs are organisms that obtain energy by the oxidation of electron donors in their environments. These molecules can be organic or inorganic . The chemotroph designation is in contrast to phototrophs, which utilize solar energy...
that have colonized Lōihi. Lōihi's extensive vent system
Hydrothermal vent
A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both...
is characterized by a high concentration of CO2 and Iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, while being low in sulfide. These characteristics make a perfect environment for iron-oxidizing bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, called FeOB, to thrive in.
Hydrothermal vent geochemistry
Lōihi's mid-Pacific location and its well-sustained hydrothermal system contribute to a rich oasis for a microbial ecosystemEcosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
. Areas of extensive hydrothermal vent
Hydrothermal vent
A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both...
ing are found on Lōihi's crater floor
Volcanic crater
A volcanic crater is a circular depression in the ground caused by volcanic activity. It is typically a basin, circular in form within which occurs a vent from which magma erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of great depth...
and north slope, and along the summit of Lōihi itself. Active hydrothermal vents were first discovered at Lōihi in the late 1980s. These vents are remarkably similar to those found at the mid-ocean ridge
Mid-ocean ridge
A mid-ocean ridge is a general term for an underwater mountain system that consists of various mountain ranges , typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading...
s, with similar composition and thermal differences. The two most prominent vent fields are at the summit: Pele's Pit (formally Pele's Vents) and Kapo's Vents. They are named after the Hawaiian deity
Deity
A deity is a recognized preternatural or supernatural immortal being, who may be thought of as holy, divine, or sacred, held in high regard, and respected by believers....
Pele and her sister Kapo
Kapo (mythology)
In Hawaiian mythology, Kapo is a goddess of fertility, sorcery and dark powers who can assume any shape she wills. She is the mother of Laka, although some versions have them as the same goddess...
. These vents were considered "low temperature vents" because their waters were only about 30 °C. The volcanic eruption of 1996 and the creation of Pele's Pit changed this, and initiated high temperature venting; exit temperatures were measured at 77 °C in 1996.
| Vent | Depth | Location | Notes |
|---|---|---|---|
| Pele's | 1000 m (3,281 ft) | Summit | destroyed 1996 |
| Kapo's | 1280 m (4,199 ft) | Upper South rift | No longer venting |
| Forbidden | 1160 m (3,806 ft) | Pele's Pit | over 200 °C |
| Lohiau ("slow") | 1173 m (3,848.4 ft) | Pele's Pit | 77 °C |
| Pahaku ("rocky") | 1196 m (3,924 ft) | South rift zone | 17 °C |
| Ula ("red") | 1099 m (3,606 ft) | South summit | Diffuse venting |
| Maximilian | 1249 m (4,098 ft) | West summit flank | Diffuse venting |
| Naha | 1325 m (4,347 ft) | South rift | 23 °C |
Microorganisms
The vents lie 1100 m (3,608.9 ft) to 1325 m (4,347.1 ft) below the surface, and range in temperatureTemperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
from 10 to over . The vent fluids are characterized by a high concentration of (up to 17 mM) and Fe (Iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
), but low in sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
. Low oxygen and pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
levels are important factors in supporting the high amounts of Fe (iron), one of the hallmark features of Lōihi. These characteristics make a perfect environment for iron-oxidizing bacteria, called FeOB, to thrive in. An example of these species is Mariprofundus ferrooxydans
Mariprofundus ferrooxydans
Mariprofundus ferrooxydans is a neutrophilic chemolithotrophic gram-negative bacterium which can grow by oxidising ferrous to ferric iron. It is the sole member of the class Zetaproteobacteria in the phylum Proteobacteria...
, sole member of the class Zetaproteobacteria
Zetaproteobacteria
Zetaproteobacteria is a class of Proteobacteria, which is composed of a sole member, Mariprofundus ferrooxydans described in 2010, falling basal to the gamma and betaproteobacteria and confirmed by other studies...
. The composition of the materials was similar to that of black smokers, that are a habitat of archaea extremophiles
Extremophile
An extremophile is an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth. In contrast, organisms that live in more moderate environments may be termed mesophiles or neutrophiles...
. Dissolution
Dissolution (chemistry)
Dissolution is the process by which a solid, liquid or gas forms a solution in a solvent. In solids this can be explained as the breakdown of the crystal lattice into individual ions, atoms or molecules and their transport into the solvent. For liquids and gases, the molecules must be compatible...
and oxidation of the mineral observed over the next two years suggests the sulfate is not easily preserved.
A diverse community of microbial mat
Microbial mat
A microbial mat is a multi-layered sheet of micro-organisms, mainly bacteria and archaea. Microbial mats grow at interfaces between different types of material, mostly on submerged or moist surfaces but a few survive in deserts. They colonize environments ranging in temperature from –40°C to +120°C...
s surround the vents and virtually cover Pele's Pit.
The Hawaii Undersea Research Laboratory
Hawaii Undersea Research Laboratory
The Hawaii Undersea Research Laboratory is a regional undersea research facility under the auspices of the U. S. government's National Oceanic and Atmospheric Administration National Undersea Research Program and administered by the University of Hawaii. Its headquarters are at University of...
(HURL), NOAA's Research Center for Hawaii and the Western Pacific, monitors and researches the hydrothermal systems and studies the local community.
The National Science Foundation
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...
(NSF
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...
) funded an extremophile
Extremophile
An extremophile is an organism that thrives in physically or geochemically extreme conditions that are detrimental to most life on Earth. In contrast, organisms that live in more moderate environments may be termed mesophiles or neutrophiles...
sampling expedition to Lōihi in 1999. Microbial mats surrounded the 160 °C vents, and included a novel jelly
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
-like organism. Samples were collected for study at NSF's Marine Bioproducts Engineering Center (MarBEC). In 2001, Pisces V collected samples of the organisms and brought them to the surface for study.
NOAA's National Undersea Research Center and NSF's Marine Bioproducts Engineering Center are cooperating to sample and research the local bacteria and archaea extremophiles. The fourth FeMO (Fe-Oxidizing Microbial Observatory) cruise occurred during October 2009.
Macroorganisms
Marine life inhabiting the waters around Lōihi is not as diverse as life at other, less active seamounts. Fish found living near Lōihi include the Celebes monkfish (Sladenia remigerGoosefish
Monkfish are a family, Lophiidae, of anglerfishes. They are found in the Arctic, Atlantic, Indian and Pacific Oceans where they live on sandy and muddy bottoms of the continental shelf and continental slope, at depths in excess of ....
), and members of the Cutthroat eel family, Synaphobranchidae
Cutthroat eel
Cutthroat eels are a family, Synaphobranchidae, of eels, the only member of the suborder Synaphobranchoidei. They are found worldwide in temperate and tropical seas....
. Invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s identified in the area include two species endemic to the hydrothermal vents, a bresiliid shrimp
Bresilioidea
Bresilioidea is a superfamily of shrimp. It is likely to be an artificial group, containing five families which may or may not be related....
(Opaepele loihi) of the family Alvinocarididae
Alvinocarididae
Alvinocarididae is a family of shrimp, originally described by M. L. Christoffersen in 1986 from samples collected by DSV Alvin, from which they derive their name. Shrimp of the family Alvinocarididae generally inhabit deep sea hydrothermal vent regions, and hydrocarbon cold seep environments....
(described in 1995), and a tube or pogonophoran worm
Siboglinidae
Siboglinidae, also known as the beard worms, is a family of polychaete annelid worms whose members made up the former phyla Pogonophora and Vestimentifera. They are composed of about 100 species of vermiform creatures and live in thin tubes buried in sediments at ocean depths from 100 to 10,000 m...
. Dives conducted after the 1996 earthquake swarms were unable to find either the shrimp or the worm, and it is not known if there are lasting effects on these species.
From 1982 to 1992, researchers in Hawaii Undersea Research Laboratory
National Undersea Research Program
The National Underwater Research Program is a U.S. government program that operates six facilities for undersea research, including the world's only permanent undersea research facility, Aquarius. The program is operated under the auspices of the Office of Oceanic and Atmospheric Research, a...
submersible
Submersible
A submersible is a small vehicle designed to operate underwater. The term submersible is often used to differentiate from other underwater vehicles known as submarines, in that a submarine is a fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersible is...
s photographed the fish of Lōihi Seamount, Johnston Atoll
Johnston Atoll
Johnston Atoll is a atoll in the North Pacific Ocean about west of Hawaii. There are four islands located on the coral reef platform, two natural islands, Johnston Island and Sand Island, which have been expanded by coral dredging, as well as North Island and East Island , an additional two...
, and Cross Seamount
Cross Seamount
Cross Seamount is a seamount far southwest of the Hawaii archipelago, about equidistant from the cities of Honolulu and Kona. It is one of the numerous seamounts surrounding Hawaii, although unrelated to the Hawaiian hotspot...
at depths between 40 m (131.2 ft) and 2000 m (6,561.7 ft). A small number of species identified at Lōihi were newly recorded sightings in Hawaii, including the Tassled coffinfish (Chaunax fimbriatus
Sea toad
Coffinfish are a family, Chaunacidae, of deep-sea anglerfishes.They are bottom-dwelling fishes found on the continental slopes of the Atlantic, Indian and Pacific Oceans, at depths of up to ....
), and the Celebes monkfish.
Further reading
ihi Seamount by the Hawaii Undersea Geo-Observatory| journal = Geochemistry Geophysics Geosystems
| volume = 2
| issue = 5
| pages = 1525–2027
| publisher = American Geophysical Union
American Geophysical Union
The American Geophysical Union is a nonprofit organization of geophysicists, consisting of over 50,000 members from over 135 countries. AGU's activities are focused on the organization and dissemination of scientific information in the interdisciplinary and international field of geophysics...
and the Geochemical Society
Geochemical Society
The Geochemical Society is a nonprofit and international scientific society for the purpose of encouraging the application of chemistry to solve problems involving geology and cosmology...
| date = 2001-05-25
| url = http://erda.sdsc.edu/bgfiles/aalf/aalf0005827doc01.pdf
| issn = 1525-2027
| doi = 10.1029/2000GC000113
| accessdate = 2009-04-27 }}i Press
| year = 1998
| isbn = 0-8248-2003-7
}}ihi volcano, Hawaii
| journal = EOS Trans. Am. Geophys. Union
Eos (journal)
Eos, Transactions, American Geophysical Union, a publication of the American Geophysical Union, is a weekly newspaper of geophysics that carries refereed articles on current research and on the relationship of geophysics to social and political questions, news, book reviews, AGU journal and meeting...
| volume = 78
| issue = 22
| pages = 229–33
| publisher =
| location =
| date = 1997-06-03
| url = http://www.soest.hawaii.edu/~sansone/Duennebier%20et%20al%201997%20Eos.pdf
| doi = 10.1029/97EO00150
| accessdate =
| bibcode=1997EOSTr..78Q.229T
}}i
| journal = Pacific Science
Pacific Science
Pacific Science is an international, multidisciplinary, academic journal devoted to the biological and physical sciences of the Pacific basin, focusing especially on biogeography, ecology, evolution, geology and volcanology, oceanography, palaeontology, and systematics...
| volume = 9
| issue =
| pages = 286–91
| publisher = University of Hawaii Press
| location =
| year = 1955
| accessdate =
}}
ihi submarine volcano and the Hawaiian hot spot
| journal = Journal of Geophysical Research
| volume = 87
| issue =
| pages = B9
| publisher =
| location =
| year = 1982
| issn = 0148-0227
| accessdate =
}}
- Macdonald, G.A. (1952). "The South Hawaii Earthquakes of March and April, 1952." The Volcano Letter. U.S. Geological Survey Professional Paper 515.ihi, Hawaii
| journal = Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
| volume = 298
| issue = 5871
| pages = 234–39
| publisher = Nature Publishing Group
| location =
| date = 1982-07-15
| url = http://www.nature.com/nature/journal/v298/n5871/abs/298234a0.html
| doi = 10.1038/298234a0
| accessdate =
}}ihi Seamount, Hawaii
| journal = Geology
| volume = 10
| issue = 2
| pages = 88–92
| publisher = Geological Society of America
| location =
| year = 1982| date = Feb., 1982
| url =
| doi = 10.1130/0091-7613(1982)10<88:DBTFLS>2.0.CO;2
| accessdate =
}}
- Scripps Institution of OceanographyScripps Institution of OceanographyScripps Institution of Oceanography in La Jolla, California, is one of the oldest and largest centers for ocean and earth science research, graduate training, and public service in the world...
. (2002). Benthic Invertebrate Collection Database.
External links
- Hawaii Center for Volcanology, University of Hawaii.
- Loihi Seamount—USGS website.
- Loihi Submarine Volcano: A unique, natural extremophile laboratory—NOAA research site.
- HURL Current Research – Loihi after the July–August event, on the 1996 Lōihi Seamount Exploration
- Recent volcanic activity at Loihi – University of Hawaii
- Fe-Oxidizing Microbial Observatory Project (FeMO) Webpage – Earthref.org