Lōihi Seamount (also known as Lōʻihi) is an active submarine volcano about 35 km (22 mi) off the southeast coast of the island of Hawaii. The top of the seamount is about 975 m (3,000 ft) below sea level. This seamount is on the flank of Mauna Loa, the largest shield volcano on Earth. Lōihi, meaning "long" in Hawaiian, is the newest volcano in the Hawaiian–Emperor seamount chain, a string of volcanoes that stretches over 5,800 km (3,600 mi) northwest of Lōʻihi. Unlike most active volcanoes in the Pacific Ocean that make up the active plate margins on the Pacific Ring of Fire, Lōʻihi 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, Lōʻihi Seamount stands more than 3,000 m (10,000 ft) above the seafloor, making it taller than Mount St. Helens was before its catastrophic 1980 eruption. A diverse microbial community resides around Lōihi's many hydrothermal vents.
In the summer of 1996, a swarm of 4,070 earthquakes was recorded at Lōʻihi. At the time this was the most energetic earthquake swarm in Hawaii recorded history. The swarm altered 10 to 13 square kilometres (4 to 5 sq mi) 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 United States Geological Survey (USGS). The Hawaii Undersea Geological Observatory (HUGO) provided real-time data on Lōʻihi between 1997 and 1998. Lōʻihi's last known eruption was in 1996, before the earthquake swarm of that summer.
Yellow iron oxide-covered lava rock on the flank of Lōʻihi
|Summit depth||975 m (3,199 ft).|
|Height||over 3,000 m (10,000 ft) above the ocean floor|
|Summit area||Volume – 660 km3 (160 mi3)|
|Translation||"long" (from Hawaiian)|
|Location||Southeast of the island of Hawaiʻi, Hawaii, U.S.|
|Volcanic arc/chain||Hawaiian–Emperor seamount chain|
|Age of rock||At least 400,000 years old|
|Last eruption||February to August 1996|
|Discovery date||1940 – US Coast and Geodetic Survey chart number 4115|
Lōʻihi is a seamount, or underwater volcano, on the flank of Mauna Loa, the Earth's largest shield volcano. It is the newest volcano created by the Hawaiʻi hotspot in the extensive Hawaiian–Emperor seamount chain. The distance between the summit of the older Mauna Loa and the summit of Lōʻihi is about 80 km (50 mi), which is, coincidentally, also the approximate diameter of the Hawaiʻi hotspot. Lōʻihi consists of a summit area with three pit craters, 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 craters 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 (700 ft) high and were formed in July 1996 when its predecessor, Pele's Vent, a hydrothermal field near Lōʻihi's summit, collapsed into a large depression. The thick crater walls of Pele's Pit – averaging 20 m (70 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 (200–260 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 80–100 million 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 80–100 million years, the sea floor under Hawaii moved from the East Pacific Rise to its present location 6,000 km (4,000 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.
Lōʻihi is built on the seafloor with a slope of about five degrees. Its northern base on the flank of Mauna Loa is 1,900 m (6,200 ft) below sea level, but its southern base is a more substantial 4,755 m (15,600 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 3,786 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. Lōʻihi 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 the early development of Hawaiian volcanoes. Lōʻihi is predicted to rise above the surface in 10,000 to 100,000 years.
Radiometric dating was used to determine the age of rock samples from Lōʻihi. 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 recent 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 Lōʻihi is about 400,000 years old. The rock accumulates at an average rate of 3.5 mm (0.14 in) per year near the base, and 7.8 mm (0.31 in) near the summit. If the data model from other volcanoes such as Kīlauea holds true for Lōʻihi, 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, Lōʻihi was 40 km (25 mi) southeast of its current position at the time of its initial eruption.
Lōihi is a young and fairly active volcano, although less active than nearby Kīlauea. In the past few decades, several earthquake swarms 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 1990-1971 earthquake, lasting several months, and the 1996 event, which was shorter but much more pronounced. The 1996 event was directly observed by an ocean bottom seismometer (OBS), 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 Lōʻihi'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 waves and to investigate the relationship between earthquakes and eruptions. This low level activity is periodically punctuated by large swarms of earthquakes, each swarm composed of 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 Lōʻihi. The largest recorded swarms took place on Lōihi in 1971, 1972, 1975, 1991–92 and 1996. The nearest seismic station is around 30 km (20 mi) from Lōʻihi, 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.
|Evidence of eruption in early 1996, and large, well-recorded earthquake swarm in the summer. Started on February 25, 1996, and lasted until August 9, 1996.|
|An OBO positioned on the seamount to track a recent earthquake swarm collected evidence of deflation, possibly due to magma withdrawal.|
|Possible eruption, occurred on September 20, 1986 (one day).|
|Nine events of magnitude 3 or greater, measuring between 3.0 and 4.2, were recorded from November 11, 1984, to January 21, 1985. Eruption possible, but uncertain.|
|Prominent earthquake swarm from August 24, 1975, to November 1975.|
|Possible eruption from September 17, 1971, to September 1972. Eruption uncertain.|
|An earthquake swarm on Lōʻihi in 1952 was the event that first brought attention to the volcano, previously thought extinct.|
|Confirmed ancient eruption|
|Confirmed ancient eruption|
|Confirmed ancient eruption, most likely on the east flank|
|This table indexes only possible volcanic eruptions and major events. Lōʻihi 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 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 rapid 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 Lōʻihi 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 Lōʻihi's summit had collapsed, a result of a swarm of earthquakes and the rapid withdrawal of magma from the volcano. A crater 1 km (0.6 mi) across and 300 m (1,000 ft) deep formed out of the rubble. The event involved the movement of 100 million 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". Strong currents make 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 ridges. 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 1,325 m (4,350 ft).
Lōʻihi 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, magnitudes 5.1 and 5.4, on May 13 and July 17. Both originated from a depth of 44 km (27 mi). On April 23, a magnitude 4.3 earthquake was recorded at a depth of approximately 33 km (21 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 Hawaii (Island)).
Lōʻihi Seamount's first depiction on a map was on Survey Chart 4115, a bathymetric rendering of part of Hawaiʻi 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, similar to the two active Hawaiian volcanoes, Mauna Loa and Kīlauea. Macdonald's hypothesis placed the seamount as the newest volcano in the Hawaiian–Emperor seamount chain, created by the Hawaiʻi hotspot. However, because the earthquakes were oriented east–west (the direction of the volcanic fault) and there was no volcanic tremor in seismometers 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 Loihi. The Hawaiian word lōʻihi means "long". In 1978, an expedition studied intense, repeated seismic activity known as earthquake swarms in and around the Lōʻihi area. Rather than finding an old, extinct seamount, data collected revealed Lōʻihi to be a young, possibly active volcano. Observations showed the volcano to be encrusted with young and old lava flows. Fluids erupting from active hydrothermal vents were also found.
In 1978, a US Geological Survey research ship collected dredge samples and photographed Lōʻihi's summit with the goal of studying whether Lōʻihi is active. Analysis of the photos and testing of pillow lava rock samples appeared to show that the material was "fresh", yielding more evidence that Lōʻihi 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 Hawaiʻi hotspot, which supplies Lōʻihi with magma. Following a 1986 seismic event, a network of five ocean bottom observatories (OBOs) were deployed on Lōʻihi for a month. Lōʻihi's frequent seismicity makes it an ideal candidate for seismic study through OBOs. In 1987, the submersible DSV Alvin was used to survey Lōʻihi. Another autonomous observatory was positioned on Lōʻihi in 1991 to track earthquake swarms.
The bulk of information about Lōʻihi 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 surveys confirmed changes in the energy, and dissolved minerals emanating from Lōʻihi. Hawaiʻi Undersea Research Laboratory, HURL's 2,000 m (6,562 ft) submersible Pisces V allowed scientists to sample the vent waters, microorganisms and hydrothermal mineral deposits.
Since 2006, the Fe-Oxidizing Microbial Observatory (FeMO), funded by the National Science Foundation and Microbial Observatory Program, has led cruises to Lōʻihi investigate its microbiology 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 that have colonized Lōʻihi. Lōʻihi's extensive vent system is characterized by a high concentration of CO2 and Iron, while being low in sulfide. These characteristics make a perfect environment for iron-oxidizing bacteria, called FeOB, to thrive in.
In 1997, scientists from the University of Hawaiʻi installed an ocean bottom observatory on the summit of Lōʻihi Seamount. The submarine observatory was nicknamed HUGO, (Hawaiʻi Undersea Geological Observatory). HUGO was connected to the shore, 34 km (21 mi) away, by a fiber optic cable. It was designed to give scientists real-time seismic, chemical and visual data about the state of Lōʻihi, 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 April 1998, effectively shutting it down. The observatory was recovered from the seafloor in 2002.
|Pele's||1,000 m (3,281 ft)||Summit||Destroyed 1996|
|Kapo's||1,280 m (4,199 ft)||Upper South rift||No longer venting|
|Forbidden||1,160 m (3,806 ft)||Pele's Pit||over 200 °C|
|Lohiau ("slow")||1,173 m (3,850 ft)||Pele's Pit||77 °C|
|Pahaku ("rocky")||1,196 m (3,924 ft)||South rift zone||17 °C|
|Ula ("red")||1,099 m (3,606 ft)||South summit||Diffuse venting|
|Maximilian||1,249 m (4,098 ft)||West summit flank||Diffuse venting|
|Naha||1,325 m (4,347 ft)||South rift||23 °C|
Lōʻihi's mid-Pacific location and its well-sustained hydrothermal system contribute to a rich oasis for a microbial ecosystem. Areas of extensive hydrothermal venting are found on Lōʻihi's crater floor and north slope, and along the summit of Lōʻihi itself. Active hydrothermal vents were first discovered at Lōʻihi in the late 1980s. These vents are remarkably similar to those found at the mid-ocean ridges, 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 Pele and her sister Kapo. 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.
The vents lie 1,100 m (3,600 ft) to 1,325 m (4,347 ft) below the surface, and range in temperature from 10 to over 200 °C. The vent fluids are characterized by a high concentration of CO
2 (up to 17 mM) and Fe (Iron), but low in sulfide. Low oxygen and pH levels are important factors in supporting the high amounts of Fe (iron), one of the hallmark features of Lōʻihi. These characteristics make a perfect environment for iron-oxidizing bacteria, called FeOB, to thrive in. An example of these species is Mariprofundus ferrooxydans, sole member of the class Zetaproteobacteria. The composition of the materials was similar to that of black smokers, that are a habitat of archaea extremophiles. Dissolution and oxidation of the mineral observed over the next two years suggests the sulfate is not easily preserved.
A diverse community of microbial mats surround the vents and virtually cover Pele's Pit. The Hawaiʻi Undersea Research Laboratory (HURL), NOAA's Research Center for Hawaiʻi and the Western Pacific, monitors and researches the hydrothermal systems and studies the local community. The National Science Foundation (NSF) funded an extremophile sampling expedition to Lōʻihi in 1999. Microbial mats surrounded the 160 °C vents, and included a novel jelly-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.
Marine life inhabiting the waters around Lōʻihi is not as diverse as life at other, less active seamounts. Fish found living near Lōʻihi include the Celebes monkfish (Sladenia remiger), and members of the Cutthroat eel family, Synaphobranchidae. Invertebrates identified in the area include two species endemic to the hydrothermal vents, a bresiliid shrimp (Opaepele loihi) of the family Alvinocarididae (described in 1995), and a tube or pogonophoran worm. 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 Hawaiʻi Undersea Research Laboratory submersibles photographed the fish of Lōʻihi Seamount, Johnston Atoll, and Cross Seamount at depths between 40 m (130 ft) and 2,000 m (6,600 ft). A small number of species identified at Lōʻihi were newly recorded sightings in Hawaiʻi, including the Tassled coffinfish (Chaunax fimbriatus), and the Celebes monkfish.
The only two vent-specific macrofaunal species described from Loihi have been a novel bresiliid shrimp, Opaepele loihi (Williams and Dobbs, 1995), and a unique lineage of pogonophoran worm (R. Vrijenhoek, pers. comm.). The post-event dives, however, found no evidence for either, and the long-term impact of the event on these species is unknown.
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. Carotenoid pigment has been found in their bodies. The family Alvinocarididae comprises 7 extant genera.Darlene Lim
Darlene Sze Shien Lim is a NASA geobiologist and exobiologist preparing astronauts for the scientific exploration of the Moon, Deep Space and Mars. Her expertise involves Mars human analog missions, in which extreme landscapes like volcanoes and Arctic deserts serve as physical or operational substitutes for various planetary bodies. She has become a leading public figure for Mars exploration, having presented her missions publicly at academic institutions and public events around the world. She has also discussed her work for various media groups such as NPR, The New York Times, and The Washington Post.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 5,800 kilometres (3,600 mi) across the North Pacific Ocean, called the Hawaiian-Emperor seamount chain. Hawaiʻi's volcanoes rise an average of 4,572 metres (15,000 ft) to reach sea level from their base. The largest, Mauna Loa, is 4,169 metres (13,678 ft) high. As shield volcanoes, they are built by accumulated lava flows, growing a few meters/feet at a time to form a broad and gently sloping shape.Hawaiian islands undergo a systematic pattern of submarine and subaerial growth that is followed by erosion. An island's stage of development reflects its distance from the Hawaii hotspot.Hawaii
Hawaii ( (listen) hə-WY-ee; Hawaiian: Hawaiʻi [həˈvɐjʔi]) is a state of the United States of America. It is the only state located in the Pacific Ocean and the only state composed entirely of islands.
The state encompasses nearly the entire Hawaiian archipelago, 137 islands spread over 1,500 miles (2,400 km). The volcanic archipelago is physiographically and ethnologically part of the Polynesian subregion of Oceania. At the southeastern end of the archipelago, the eight main islands are, in order from northwest to southeast: Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Kahoʻolawe, Maui, and Hawaiʻi. The last is the largest island in the group; it is often called the "Big Island" or "Hawaiʻi Island" to avoid confusion with the state or archipelago.
Hawaii is the 8th smallest geographically and the 11th least populous, but the 13th most densely populated of the 50 states. It is the only state with an Asian American plurality. Hawaii has over 1.4 million permanent residents, along with many visitors and U.S. military personnel. The state capital and largest city is Honolulu on the island of Oʻahu. The state's ocean coastline is about 750 miles (1,210 km) long, the fourth longest in the U.S., after the coastlines of Alaska, Florida, and California. Hawaii is the most recent state to join the union, on August 21, 1959. It was an independent nation until 1898.
Hawaii's diverse natural scenery, warm tropical climate, abundance of public beaches, oceanic surroundings, and active volcanoes make it a popular destination for tourists, surfers, biologists, and volcanologists. Because of its central location in the Pacific and 19th-century labor migration, Hawaii's culture is strongly influenced by North American and East Asian cultures, in addition to its indigenous Hawaiian culture.Hawaii Undersea Research Laboratory
The Hawaii Undersea Research Laboratory (HURL) is a regional undersea research program within the School of Ocean and Earth Sciences and Technology (SOEST) at University of Hawaii at Manoa, in Honolulu. It is considered one of the more important of the independently run undersea research laboratories in the U.S. HURL operates two deep diving submersibles, the Pisces IV and Pisces V and specializes in supporting scientific ocean research and exploration. HURL is actively involved in monitoring deep-sea ecosystems, including coral habitats and fisheries, and conducts maritime archaeology research including documenting World War II wreckage from the Attack on Pearl Harbor in 1941.Hawaii hotspot
The Hawaii hotspot is a volcanic hotspot located near the namesake Hawaiian Islands, in the northern Pacific Ocean. One of the best known and intensively studied hotspots in the world, the Hawaii plume is responsible for the creation of the Hawaiian–Emperor seamount chain, a 5,800-kilometre (3,600 mi) mostly undersea volcanic mountain range. Four of these volcanoes are active, two are dormant; more than 123 are extinct, most now preserved as atolls or seamounts. The chain extends from south of the island of Hawaiʻi to the edge of the Aleutian Trench, near the eastern coast of Russia.
While most volcanoes are created by geological activity at tectonic plate boundaries, the Hawaii hotspot is located far from plate boundaries. The classic hotspot theory, first proposed in 1963 by John Tuzo Wilson, proposes that a single, fixed mantle plume builds volcanoes that then, cut off from their source by the movement of the Pacific Plate, become increasingly inactive and eventually erode below sea level over millions of years. According to this theory, the nearly 60° bend where the Emperor and Hawaiian segments of the chain meet was caused by a sudden shift in the movement of the Pacific Plate. In 2003, fresh investigations of this irregularity led to the proposal of a mobile hotspot theory, suggesting that hotspots are mobile, not fixed, and that the 47-million-year-old bend was caused by a shift in the hotspot's motion rather than the plate's.
Ancient Hawaiians were the first to recognize the increasing age and weathered state of the volcanoes to the north as they progressed on fishing expeditions along the islands. The volatile state of the Hawaiian volcanoes and their constant battle with the sea was a major element in Hawaiian mythology, embodied in Pele, the deity of volcanoes. After the arrival of Europeans on the island, in 1880–1881 James Dwight Dana directed the first formal geological study of the hotspot's volcanics, confirming the relationship long observed by the natives. The Hawaiian Volcano Observatory was founded in 1912 by volcanologist Thomas Jaggar, initiating continuous scientific observation of the islands. In the 1970s, a mapping project was initiated to gain more information about the complex geology of Hawaii's seafloor.
The hotspot has since been tomographically imaged, showing it to be 500 to 600 km (310 to 370 mi) wide and up to 2,000 km (1,200 mi) deep, and olivine and garnet-based studies have shown its magma chamber is approximately 1,500 °C (2,730 °F). In its at least 85 million years of activity the hotspot has produced an estimated 750,000 km3 (180,000 cu mi) of rock. The chain's rate of drift has slowly increased over time, causing the amount of time each individual volcano is active to decrease, from 18 million years for the 76-million-year-old Detroit Seamount, to just under 900,000 for the one-million-year-old Kohala; on the other hand, eruptive volume has increased from 0.01 km3 (0.002 cu mi) per year to about 0.21 km3 (0.050 cu mi). Overall, this has caused a trend towards more active but quickly-silenced, closely spaced volcanoes—whereas volcanoes on the near side of the hotspot overlap each other (forming such superstructures as Hawaiʻi island and the ancient Maui Nui), the oldest of the Emperor seamounts are spaced as far as 200 km (120 mi) apart.Hawaiian–Emperor seamount chain
The Hawaiian–Emperor seamount chain is a mostly undersea mountain range in the Pacific Ocean that reaches above sea level in Hawaii. It is composed of the Hawaiian ridge, consisting of the islands of the Hawaiian chain northwest to Kure Atoll, and the Emperor Seamounts: together they form a vast underwater mountain region of islands and intervening seamounts, atolls, shallows, banks and reefs along a line trending southeast to northwest beneath the northern Pacific Ocean. The seamount chain, containing over 80 identified undersea volcanoes, stretches about 6,200 kilometres (3,900 mi) from the Aleutian Trench in the far northwest Pacific to the Loʻihi seamount, the youngest volcano in the chain, which lies about 35 kilometres (22 mi) southeast of the Island of Hawaiʻi.Hilina Slump
The Hilina Slump, on the south flank of the Kīlauea Volcano on the southeast coast of the Big Island of Hawaiʻi, is the most notable of several landslides that ring each of the Hawaiian Islands. These landslides are the means by which material deposited at a volcano's vents are transferred downward and seaward, eventually spilling onto the seabed to broaden the island.Kīlauea's entire south flank, extending out to Cape Kumukahi, is currently sliding seaward, with some parts of the central portion (over looking the Hilina slump) moving as much as 10 centimeters (4 inches) per year, pushed by the forceful injection of magma and pulled by gravity.Current movement of the Hilina slump and recent volcanic activity, coupled with evidence of massive submarine slides in the geological past, has led to sensationalistic claims of megatsunamis that might result if the south flank of Kīlauea should suddenly fail. Geologists are confident no such failure is likely, and other experts have stated that the supposed threats of megatsunamis are exaggerated.Kohala (mountain)
Kohala is the oldest of five volcanoes that make up the island of Hawaii. Kohala is an estimated one million years old—so old that it experienced, and recorded, the reversal of earth's magnetic field 780,000 years ago. It is believed to have breached sea level more than 500,000 years ago and to have last erupted 120,000 years ago. Kohala is 606 km2 (234 sq mi) in area and 14,000 km3 (3,400 cu mi) in volume, and thus constitutes just under 6% of the island of Hawaii.Kohala is a shield volcano cut by multiple deep gorges, which are the product of thousands of years of erosion. Unlike the typical symmetry of other Hawaiian volcanoes, Kohala is shaped like a foot. Toward the end of its shield-building stage 250,000 to 300,000 years ago, a landslide destroyed the northeast flank of the volcano, reducing its height by over 1,000 m (3,300 ft) and traveling 130 km (81 mi) across the sea floor. This huge landslide may be partially responsible for the volcano's foot-like shape. Marine fossils have been found on the flank of the volcano, far too high to have been deposited by standard ocean waves. Analysis indicated that the fossils had been deposited by a massive tsunami approximately 120,000 years ago.
Because it is so far from the nearest major landmass, the ecosystem of Kohala has experienced the phenomenon of geographic isolation, resulting in an ecosystem radically different from that of other places. Invasive species introduced by man present a problem to Kohala's ecosystem, as they push native species out of their habitat. There are several initiatives to preserve Kohala's ecosystem. Crops, especially sweet potato (Ipomoea batatas), have been harvested on the Leeward side of the volcano for centuries as well. The northern part of the island is named after the mountain, with two districts named North and South Kohala. King Kamehameha I, the first King of the Kingdom of Hawaii, was born in North Kohala, near Hawi.Kīlauea
Kīlauea (, US: ; Hawaiian: [kiːlɐwˈwɛjə]) is an active shield volcano in the Hawaiian Islands that last erupted between 1983 and 2018. Historically, Kīlauea is the most active of the five volcanoes that together form the island of Hawaiʻi. Located along the southerneastern shore of the island, the volcano is between 210,000 and 280,000 years old and emerged above sea level about 100,000 years ago.
It is the second youngest product of the Hawaiian hotspot and the current eruptive center of the Hawaiian–Emperor seamount chain. Because it lacks topographic prominence and its activities historically coincided with those of Mauna Loa, Kīlauea was once thought to be a satellite of its much larger neighbor. Structurally, Kīlauea has a large, fairly recently formed caldera at its summit and two active rift zones, one extending 125 km (78 mi) east and the other 35 km (22 mi) west, as an active fault of unknown depth moving vertically an average of 2 to 20 mm (0.1 to 0.8 in) per year.
Kīlauea erupted nearly continuously from 1983 to 2018, causing considerable property damage, including the destruction of the towns of Kalapana in 1990, and Vacationland Hawaii and Kapoho in 2018. During the 2018 lower Puna eruption, which began on May 3, two dozen lava vents erupted downrift from the summit in Puna. The eruption was accompanied by a strong earthquake on May 4 of Mw 6.9, and nearly 2,000 residents were evacuated from the rural Leilani Estates subdivision and nearby areas.
On May 17, 2018 at 4:17 AM, the volcano explosively erupted at the summit in Halemaʻumaʻu, throwing ash 30,000 feet into the air. Continued explosive activity at the summit caused a months-long closure of the Kīlauea section of Hawaii Volcanoes National Park. Vigorous eruptive lava fountains in lower Puna sent destructive rivers of molten rock into the ocean in three places. The lava destroyed Hawaii's largest natural freshwater lake, covered substantial portions of Leilani Estates and Lanipuna Gardens, and completely inundated the communities of Kapoho, Vacationland Hawaii and all but three houses in the Kapoho Beach Lots. Lava also filled Kapoho Bay and extended new land nearly a mile into the sea. The County of Hawaii reported that 716 dwellings were destroyed by lava. By early August the eruption subsided substantially, and the last active lava was reported at the surface on September 4, 2018. Portions of Hawaii Volcanoes National Park reopened to the public on September 22. On December 5, 2018, after 90 days of inactivity from the volcano, the eruption that started in 1983 was declared to be over.Limu o Pele
Limu o Pele or Pele's seaweed (Hawaiian, literally "seaweed of Pele" after Pele the Hawaiian fire goddess of volcanoes) is a geological term for thin sheets and subsequently shattered flakes of brownish-green to near-colorless volcanic glass lava spatter, commonly resembling seaweed in appearance, that have been erupted from a volcano. Limu o Pele is formed when water is forced into and trapped inside lava, as when waves wash over the top of the exposed flows of the molten rock. The water boils and is instantly converted to steam, expanding to form bubbles within the lava. The lava rapidly cools and solidifies as the bubbles grow. The volcanic glass bubbles burst and are dispersed by the wind, showering flakes of glass downwind.
Limu o Pele has been found around subaerial littoral volcanic cones and also at submarine volcanoes, for example, on the summit of Lōʻihi seamount.List of volcanoes in the Hawaiian – Emperor seamount chain
The Hawaiian–Emperor seamount chain is a series of volcanoes and seamounts extending about 6,200 km across the Pacific Ocean. The chain has been produced by the movement of the ocean crust over the Hawaiʻi hotspot, an upwelling of hot rock from the Earth's mantle. As the oceanic crust moves the volcanoes farther away from their source of magma, their eruptions become less frequent and less powerful until they eventually cease to erupt altogether. At that point, erosion of the volcano and subsidence of the seafloor cause the volcano to gradually diminish. As the volcano sinks and erodes, it first becomes an atoll island and then an atoll. Further subsidence causes the volcano to sink below the sea surface, becoming a seamount and/or a guyot. This list documents the most significant volcanoes in the chain, ordered by distance from the hotspot; however, there are many others that have yet to be properly studied.
The chain can be divided into three subsections. The first, the Hawaiian archipelago (also known as the Windward isles), consists of the islands comprising the U.S. state of Hawaiʻi (not to be confused with the island of Hawaiʻi). As it is the closest to the hotspot, this volcanically active region is the youngest part of the chain, with ages ranging from 400,000 years to 5.1 million years. The island of Hawaiʻi is comprised by five volcanoes, of which two (Kilauea and Mauna Loa) are still active. Lōʻihi Seamount continues to grow offshore, and is the only known volcano in the chain in the submarine pre-shield stage.The second part of the chain is composed of the Northwestern Hawaiian Islands, collectively referred to as the Leeward isles, the constituents of which are between 7.2 and 27.7 million years in age. Erosion has long since overtaken volcanic activity at these islands, and most of them are atolls, atoll islands, and extinct islands. They contain many of the most northerly atolls in the world; one of them, Kure Atoll, is the northern-most atoll in the world.The oldest and most heavily eroded part of the chain are the Emperor seamounts, which are 39 to 85 million years in age. The Emperor and Hawaiian chains are separated by a large L-shaped bend that causes the orientations of the chains to differ by about 60°. This bend was long attributed to a relatively sudden change in the direction of plate motion, but research conducted in 2003 suggests that it was the movement of the hotspot itself that caused the bend. The issue is still currently under debate. All of the volcanoes in this part of the chain have long since subsided below sea level, becoming seamounts and guyots (see also the seamount and guyot stages of Hawaiian volcanism). Many of the volcanoes are named after former emperors of Japan. The seamount chain extends to the West Pacific, and terminates at the Kuril–Kamchatka Trench, a subduction zone at the border of Russia.Mariprofundus ferrooxydans
Mariprofundus ferrooxydans is a neutrophilic, chemolithotrophic, Gram-negative bacterium which can grow by oxidising ferrous to ferric iron. It is one of the only members of the class Zetaproteobacteria in the phylum Proteobacteria.Mauna Loa
Mauna Loa ( or ; Hawaiian: [ˈmɐwnə ˈlowə]; English: Long Mountain) is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaiʻi in the Pacific Ocean. The largest subaerial volcano in both mass and volume, Mauna Loa has historically been considered the largest volcano on Earth, dwarfed only by Tamu Massif. It is an active shield volcano with relatively gentle slopes, with a volume estimated at approximately 18,000 cubic miles (75,000 km3), although its peak is about 125 feet (38 m) lower than that of its neighbor, Mauna Kea. Lava eruptions from Mauna Loa are silica-poor and very fluid, and they tend to be non-explosive.
Mauna Loa has probably been erupting for at least 700,000 years, and may have emerged above sea level about 400,000 years ago. The oldest-known dated rocks are not older than 200,000 years. The volcano's magma comes from the Hawaii hotspot, which has been responsible for the creation of the Hawaiian island chain over tens of millions of years. The slow drift of the Pacific Plate will eventually carry Mauna Loa away from the hotspot within 500,000 to one million years from now, at which point it will become extinct.
Mauna Loa's most recent eruption occurred from March 24 to April 15, 1984. No recent eruptions of the volcano have caused fatalities, but eruptions in 1926 and 1950 destroyed villages, and the city of Hilo is partly built on lava flows from the late 19th century. Because of the potential hazards it poses to population centers, Mauna Loa is part of the Decade Volcanoes program, which encourages studies of the world's most dangerous volcanoes. Mauna Loa has been monitored intensively by the Hawaiian Volcano Observatory since 1912. Observations of the atmosphere are undertaken at the Mauna Loa Observatory, and of the Sun at the Mauna Loa Solar Observatory, both located near the mountain's summit. Hawaii Volcanoes National Park covers the summit and the southeastern flank of the volcano, and also incorporates Kīlauea, a separate volcano.Outline of oceanography
The following outline is provided as an overview of and introduction to Oceanography.Seamount
A seamount is a mountain rising from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to 1,000–4,000 m (3,300–13,100 ft) in height. They are defined by oceanographers as independent features that rise to at least 1,000 m (3,281 ft) above the seafloor, characteristically of conical form. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat-top seamounts are called "guyots" or "tablemounts".There are more than 14,500 seamounts, of which 9,951 seamounts and 283 guyots, covering a total of 8,796,150 km2 (3,396,210 sq mi) have been mapped but only a few have been studied in detail by scientists. Seamounts and guyots are most abundant in the North Pacific Ocean, and follow a distinctive evolutionary pattern of eruption, build-up, subsidence and erosion. In recent years, several active seamounts have been observed, for example Loihi in the Hawaiian Islands.
Because of their abundance, seamounts are one of the most common marine ecosystems in the world. Interactions between seamounts and underwater currents, as well as their elevated position in the water, attract plankton, corals, fish, and marine mammals alike. Their aggregational effect has been noted by the commercial fishing industry, and many seamounts support extensive fisheries. There are ongoing concerns on the negative impact of fishing on seamount ecosystems, and well-documented cases of stock decline, for example with the orange roughy (Hoplostethus atlanticus). 95% of ecological damage is done by bottom trawling, which scrapes whole ecosystems off seamounts.
Because of their large numbers, many seamounts remain to be properly studied, and even mapped. Bathymetry and satellite altimetry are two technologies working to close the gap. There have been instances where naval vessels have collided with uncharted seamounts; for example, Muirfield Seamount is named after the ship that struck it in 1973. However, the greatest danger from seamounts are flank collapses; as they get older, extrusions seeping in the seamounts put pressure on their sides, causing landslides that have the potential to generate massive tsunamis.