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53-753: The South Sandwich Trench is a deep arcuate trench in the South Atlantic Ocean lying 100 kilometres (62 mi) to the east of the South Sandwich Islands . It is the deepest trench of the Southern Atlantic Ocean, and the second-deepest of the Atlantic Ocean after the Puerto Rico Trench . Since the trench extends south of the 60th parallel south , it also contains the deepest point in

106-474: A snailfish at 26,250 ft (8,000 m) and a spoon worm at nearly 23,000 ft (7,000 m), the deepest level at which the species had ever been encountered. On May 7, 2019, Vescovo and Jamieson made the first human-occupied deep submersible dive to the bottom of the Sirena Deep , the third deepest point in the ocean lying about 128 miles northeast from Challenger Deep. The time they spent there

159-615: A bachelor's degree in Economics and Political Science from Stanford University , a master's degree in Defense and Arms Control Studies (Political Science) from the Massachusetts Institute of Technology , and an MBA from Harvard Business School where he was a Baker scholar . Vescovo served 20 years in the U.S. Navy Reserve as an intelligence officer, retiring in 2013 as a Commander (O-5). In 2018, Vescovo launched

212-408: A continental plate. The subducting plate, or slab , sinks into the mantle at an angle, so that there is a wedge of mantle between the slab and the overriding plate. The boundary between the subducting plate and the overriding plate coincides with a deep and narrow oceanic trench . This trench is created by the gravitational pull of the relatively dense subducting plate pulling the leading edge of

265-440: A narrow arc some distance from the trench. The distance from the trench to the volcanic arc is greater for slabs subducting at a shallower angle, and this suggests that magma generation takes place when the slab reached a critical depth for the breakdown of an abundant hydrous mineral. This would produce an ascending "hydrous curtain" that accounts for focused volcanism along the volcanic arc. However, some models suggest that water

318-428: A single subduction zone may show both aspects along its length, as part of a plate subducts beneath a continent and part beneath adjacent oceanic crust. The Aleutian Islands and adjoining Alaskan Peninsula are an example of such a subduction zone. The active front of a volcanic arc is the belt where volcanism develops at a given time. Active fronts may move over time (millions of years), changing their distance from

371-536: A volcanic arc is typically convex towards the subducting plate. This is a consequence of the spherical geometry of the Earth. The subducting plate behaves like a flexible thin spherical shell, and such a shell be bent downwards by an angle of θ, without tearing or wrinkling, only on a circle whose radius is θ/2. This means that arcs where the subducting slab descends at a shallower angle will be more tightly curved. Prominent arcs whose slabs subduct at about 45 degrees, such as

424-480: Is 965 kilometres (600 mi) long and has a maximum depth of 8,266 metres (27,119 ft) below sea level at 55°13.47′S 26°10.23′W  /  55.22450°S 26.17050°W  / -55.22450; -26.17050 , as measured by a Kongsberg EM124 multibeam sonar from February 2–7, 2019 during the Five Deeps Expedition . This measurement was made during the first complete sonar mapping of

477-408: Is continuously released from the slab from shallow depths down to 70 to 300 kilometers (43 to 186 mi), and much of the water released at shallow depths produces serpentinization of the overlying mantle wedge. According to one model, only about 18 to 37 percent of the water content is released at sufficient depth to produce arc magmatism. The volcanic arc is then interpreted as the depth at which

530-431: Is formed. Arc volcanism takes place where the slab descends out from under the cool shallow corner, allowing magma to be generated and rise through warmer, less stiff mantle rock. Magma may be generated over a broad area but become focused into a narrow volcanic arc by a permeability barrier at the base of the overriding plate. Numerical simulations suggest that crystallization of rising magma creates this barrier, causing

583-415: Is lost from the subducted plate when the temperature and pressure become sufficient to break down these minerals and release their water content. The water rises into the wedge of mantle overlying the slab and lowers the melting point of mantle rock to the point where magma is generated. While there is wide agreement on the general mechanism, research continues on the explanation for focused volcanism along

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636-553: Is low in volcanic arc rocks. Because volcanic rock is easily weathered and eroded , older volcanic arcs are seen as plutonic rocks , the rocks that formed underneath the arc (e.g. the Sierra Nevada batholith ), or in the sedimentary record as lithic sandstones . Paired metamorphic belts , in which a belt of high-temperature, low-pressure metamorphism is located parallel to a belt of low-temperature, high-pressure metamorphism, preserve an ancient arc-trench complex in which

689-615: Is particularly characteristic of volcanic arcs, though it sometimes also occurs in regions of crustal extension. In the rock record, volcanic arcs can be recognized from their thick sequences of volcaniclastic rock (formed by explosive volcanism) interbedded with greywackes and mudstones and by their calc-alkaline composition. In more ancient rocks that have experienced metamorphism and alteration of their composition ( metasomatism ), calc-alkaline rocks can be distinguished by their content of trace elements that are little affected by alteration, such as chromium or titanium , whose content

742-847: Is up to 80 kilometers (50 mi) thick, while the crust under intraoceanic arcs is 20 to 35 kilometers (12 to 22 mi) thick. Both shortening of the crust and magmatic underplating contribute to thickening of the crust. Volcanic arcs are characterized by explosive eruption of calc-alkaline magma, though young arcs sometimes erupt tholeiitic magma and a few arcs erupt alkaline magma. Calc-alkaline magma can be distinguished from tholeiitic magma, typical of mid-ocean ridges , by its higher aluminium and lower iron content and by its high content of large-ion lithophile elements, such as potassium , rubidium , caesium , strontium , or barium , relative to high-field-strength elements, such as zirconium , niobium , hafnium , rare-earth elements (REE), thorium , uranium , or tantalum . Andesite

795-599: The German survey ship Meteor , which first surveyed the area as part of its namesake expedition in 1926. The deepest point below the 60th parallel south, the deepest point in the Southern Ocean, is dubbed by Victor Vescovo as the Factorian Deep, a name that he hopes will become official. This point lies at a depth of 7,433.6 metres (24,388 ft), and is the only subzero Hadal zone in the world. The trench

848-603: The Kuril Islands , the Aleutian Islands , and the Sunda Arc , have a radius of about 20 to 22 degrees. Volcanic arcs are divided into those in which the overriding plate is continental (Andean-type arcs) and those in which the overriding plate is oceanic (intraoceanic or primitive arcs). The crust beneath the arc is up to twice as thick as average continental or oceanic crust: The crust under Andean-type arcs

901-616: The Minerve on the first dive. On the second dive, Vescovo was accompanied by Hervé Fauve, the son of the captain of the sunken submarine. They placed a commemorative plaque at the wreck. In 2021, Vescovo identified and surveyed the wreck of the USS ; Johnston  (DD-557) at a depth of 6,456 metres (21,181 ft) in the Philippine Sea ; at the time of identification this was the deepest shipwreck ever surveyed. The Johnston

954-692: The North and South Poles . Uniquely, with the successful completion of his Five Deeps Expedition, Vescovo has also dived the deepest point in each of the five world's oceans . He is the first human to have reached the bottom of the Puerto Rico Trench , the Sunda Trench , the Molloy Deep , the Sirena Deep , the Horizon Deep , and the deepest point of the Southern Ocean , which lies in

1007-630: The Pacific Ocean 's Mariana Trench . On his first descent, he piloted the DSV Limiting Factor to a depth of 10,928 m (35,853 ft), a world record by 16 m (52 ft). Diving for a second time on May 1, he became the first person to dive the Challenger Deep twice, finding "at least three new species of marine animals" and "some sort of plastic waste". Among the underwater creatures Vescovo encountered were

1060-534: The Southern Ocean . The deepest point in the entire trench is the Meteor Deep, whose location prior to February 2019 was identified as 55°25.12′S 26°24.28′W  /  55.41867°S 26.40467°W  / -55.41867; -26.40467  ( Meteor Deep ) at a depth of 8,202 metres (26,909 ft). This sounding was made during the German Meteor expedition . The depth is named after

1113-463: The oceanic trench as well as their width. A volcanic arc is part of an arc-trench complex , which is the part of a subduction zone that is visible at the Earth's surface. A subduction zone is where a tectonic plate composed of relatively thin, dense oceanic lithosphere sinks into the Earth's mantle beneath a less dense overriding plate. The overriding plate may be either another oceanic plate or

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1166-660: The 2024 ABC special Truth and Lies: Fatal Dive to the Titanic , which examined the Titan submersible implosion . In 2019, Victor Vescovo was recognized by Guinness World Records as the person who has covered the greatest vertical distance without leaving Earth's surface. As part of achieving the Explorers Grand Slam (Last Degree), Vescovo climbed Mount Everest (8,848 metres (29,029 ft)) on 24 May 2010, Earth's highest point. Almost nine years later he dove to

1219-439: The Challenger Deep, specially equipped to survey its three, well-defined basins, or "pools". Carrying three CTDs on his submersible Limiting Factor as well as one CTD and one depthometer on each of his three independent robotic "landers". Vescovo piloted six passengers to the bottom of the Challenger Deep. These included former astronaut and NOAA Administrator Kathryn Sullivan , the first woman to ultimate depth; Kelly Walsh,

1272-475: The Five Deeps Expedition, whose objective was to dive to the deepest location in all five of the world's oceans by the end of September 2019. This expedition was filmed in the documentary television series Expedition Deep Ocean . This objective was achieved one month ahead of schedule, and the expedition's team carried out biological samplings and depth confirmations at each location. Besides

1325-761: The North Pacific, with the Aleutian Arc consisting of the Aleutian Islands and their extension the Aleutian Range on the Alaska Peninsula , and the Kuril–Kamchatka Arc comprising the Kuril Islands and southern Kamchatka Peninsula . Victor Vescovo Victor Lance Vescovo (born February 10, 1966) is an American private equity investor, retired naval officer, sub-orbital spaceflight participant, and undersea explorer. He

1378-400: The arc located further from the subducting plate than the trench. The oceanic plate is saturated with water, mostly in the form of hydrous minerals such as micas , amphiboles , and serpentines . As the oceanic plate is subducted, it is subjected to increasing pressure and temperature with increasing depth. The heat and pressure break down the hydrous minerals in the plate, releasing water into

1431-451: The bottom for the first time on February 4, 2019. The deepest points of a maritime trench have historically been named after the vessel that first discovered or explored them. Volcanic arc A volcanic arc (also known as a magmatic arc ) is a belt of volcanoes formed above a subducting oceanic tectonic plate , with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench , with

1484-602: The bottom of the Challenger Deep in the Mariana Trench (−10,924 metres (−35,840 ft)), Earth's lowest point, in the deep submersible Limiting Factor on 29 April 2019, for a total vertical distance of 19,772 metres (64,869 ft). Vescovo completed the Explorers Grand Slam (Last Degree) by climbing the highest peak on each of the seven continents , and skied the Last Degree of Latitude at both

1537-535: The bottom of the Sunda Trench south of Bali , reaching the bottom of the Indian Ocean . Likewise, this was done aboard the Limiting Factor . The team reported sightings of what they believed to be species new to science, including a hadal snailfish and a gelatinous organism believed to be a stalked ascidean . The same dive was later undertaken by Patrick Lahey, President of Triton Submarines , and

1590-459: The deepest point at 60°28.46′S 025°32.32′W  /  60.47433°S 25.53867°W  / -60.47433; -25.53867 , with a depth of 7,434 metres (24,390 ft) ± 13 metres (43 ft). The expedition leader and chief submersible pilot Victor Vescovo has proposed naming this deepest point in the Southern Ocean the "Factorian Deep," based on the name of the crewed submersible DSV Limiting Factor , in which he successfully visited

1643-639: The deepest points of the five world oceans, the expedition also made dives in the Horizon Deep and the Sirena Deep , and mapped the Diamantina Fracture Zone . In December 2018, he became the first person to reach the deepest point of the Atlantic Ocean , piloting DSV Limiting Factor , a reported US$ 50 million submarine system (Triton 36000/2) – including its support ship the DSSV Pressure Drop and its three ultra-deep-sea robotic landers – 8,376 m (27,480 ft) below

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1696-402: The degree of melting becomes great enough to allow the magma to separate from its source rock. It is now known that the subducting slab may be located anywhere from 60 to 173 kilometers (37 to 107 mi) below the volcanic arc, rather than a single characteristic depth of around 120 kilometers (75 mi), which requires more elaborate models of arc magmatism. For example, water released from

1749-538: The expedition's chief scientist, Dr. Alan Jamieson . This dive was organised subsequent to the scanning of the Diamantina Fracture Zone using multibeam sonar, confirming that the Sunda Trench was deeper and settling the debate about where the deepest point in the Indian Ocean is. On April 28, 2019, Vescovo descended nearly 11 km (6.8 mi) to the deepest place in the ocean – the Challenger Deep in

1802-497: The high-temperature, low-pressure belt corresponds to the volcanic arc. In a subduction zone , loss of water from the subducted slab induces partial melting of the overriding mantle and generates low-density, calc-alkaline magma that buoyantly rises to intrude and be extruded through the lithosphere of the overriding plate. Most of the water carried downwards by the slab is contained in hydrous (water-bearing) minerals, such as mica , amphibole , or serpentinite minerals. Water

1855-515: The ocean surface to the base of the Puerto Rico Trench , an area subsequently referred to by world media as Brownson Deep . On February 4, 2019, he became the first person to reach the bottom of the Southern Ocean , in the southern portion of the South Sandwich Trench . For this attempt, the expedition used a Kongsberg EM124 multibeam sonar system to achieve accurate mapping of the trench. On April 16, 2019, Vescovo dived to

1908-577: The ocean. Unlike the Sunda and Mariana Trenches, no signs of human contamination were found in the deep, which was described by the expedition as "completely pristine". Vescovo completed the Five Deeps Expedition on 24 August 2019 when he reached a depth of 5,550 m (18,210 ft) at the bottom of the Molloy Deep in the Arctic Ocean . He was the first human to reach this location. In 2019, Vescovo escorted Titanic -historian Parks Stephenson to

1961-416: The overlying mantle. Volatiles such as water drastically lower the melting point of the mantle , causing some of the mantle to melt and form magma at depth under the overriding plate. The magma ascends to form an arc of volcanoes parallel to the subduction zone. Volcanic arcs are distinct from volcanic chains formed over hotspots in the middle of a tectonic plate. Volcanoes often form one after another as

2014-523: The plate downward. Multiple earthquakes occur within the subducting slab with the seismic hypocenters located at increasing depth under the island arc: these quakes define the Wadati–Benioff zones . The volcanic arc forms on the overriding plate over the point where the subducting plate reaches a depth of roughly 120 kilometres (75 mi) and is a zone of volcanic activity between 50 and 200 kilometers (31 and 124 mi) in width. The shape of

2067-442: The plate moves over the hotspot, and so the volcanoes progress in age from one end of the chain to the other. The Hawaiian Islands form a typical hotspot chain, with the older islands to the northwest and Hawaii Island itself, which is just 400,000 years old, at the southeast end of the chain over the hotspot. Volcanic arcs do not generally exhibit such a simple age-pattern. There are two types of volcanic arcs: In some situations,

2120-456: The precision of the new survey. This new deepest point is part of the same subsurface feature as the previous Meteor Deep location so the expedition recommended keeping the old name. Pressure Drop completed an entire survey of the trench on February 9, 2019, and made the data publicly available to GEBCO in 2019. Approximately ten other major subsurface features including various deeps, seamounts, and ridges—previously unidentified—were mapped by

2173-410: The released water lowers the melting point of the overlying mantle wedge enough for melting. The location of the volcanic arc may be determined by the presence of a cool shallow corner at the tip of the mantle wedge, where the mantle rock is cooled by both the overlying plate and the slab. Not only does the cool shallow corner suppress melting, but its high stiffness hinders the ascent of any magma that

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2226-698: The remaining magma to pool in a narrow band at the apex of the barrier. This narrow band corresponds to the overlying volcanic arc. Two classic examples of oceanic island arcs are the Mariana Islands in the western Pacific Ocean and the Lesser Antilles in the western Atlantic Ocean. The Cascade Volcanic Arc in western North America and the Andes along the western edge of South America are examples of continental volcanic arcs. The best examples of volcanic arcs with both sets of characteristics are in

2279-412: The slab at moderate depths might react with amphibole minerals in the lower part of the mantle wedge to produce water-rich chlorite . This chlorite-rich mantle rock is then dragged downwards by the subducting slab, and eventually breaks down to become the source of arc magmatism. The location of the arc depends on the angle and rate of subduction, which determine where hydrous minerals break down and where

2332-617: The small South Sandwich plate . The South Sandwich Islands constitute a volcanic island arc which results from this active subduction. Mount Belinda on Montagu Island is an active volcano . In February 2019, however, the Five Deeps Expedition, led by its survey ship DSSV  Pressure Drop , has recommended that the location of the Meteor Deep be "relocated" to the newly discovered, truly deepest location at 55°13.47′S 26°10.23′W  /  55.22450°S 26.17050°W  / -55.22450; -26.17050 and 8,266 metres (27,119 ft) ± 13 metres (43 ft) in depth, given

2385-501: The son of Don Walsh (who with Jacques Piccard made the first dive into the Challenger Deep) to become the only father/son team to make this journey albeit 60 years apart; and Vanessa O'Brien , the first woman to both climb Mount Everest and also descend to the bottom of the seafloor (Vescovo was the first person). At the end of his 2022 dives, Vescovo had the unique record of fifteen total dives to Challenger Deep, including

2438-491: The southern end of the South Sandwich Trench . He is also the first to have dived the Challenger Deep more than once, doing so fifteen times, as well as the first to have visited all four of the ocean's 10,000+ meter deepest points: the Challenger Deep/Mariana Trench, Horizon Deep/Tonga Trench, Scholl Deep/Kermadec Trench, and Galathea Deep/Philippine Trench. In June 2020, Vescovo returned to

2491-597: The trench which covered its entire length, with a measurement error of +/- 11 metres (36 ft). The deepest point of the South Sandwich Trench is only 110 metres (361 ft) shallower than the deepest point in the Puerto Rico Trench , sometimes known as the Milwaukee or Brownson Deep . The trench is produced by the subduction of the southernmost portion of the South American plate beneath

2544-526: The vessel and new names for the features were submitted to the International Hydrographic Organization (IHO) in 2019. The southernmost portion of the South Sandwich Trench reaches south of 60°S latitude and is therefore in the Southern Ocean . The maximum depth of that ocean is also in the South Sandwich Trench, which was surveyed by the Five Deeps Expedition in early February 2019. The expedition's sonar team identified

2597-580: The wreck of the RMS Titanic for the first revisit of the wreck in 15 years. Findings included continued extensive corrosion and bacterial growth on iron and steel surfaces. In February 2020, Vescovo piloted his deep diving submersible twice to the wreck of the French submarine Minerve in the Mediterranean Sea. The retired French Rear Admiral Jean-Louis Barbier investigated the wreck of

2650-453: The wreck of the Titanic inside OceanGate's Titan submersible . On Twitter Vescovo stated: "This has been a difficult week for the submersible community. Deep ocean diving is very safe when industry standard certifications and procedures are followed. I will miss my good friends PH Nargeolet, who I worked with closely, and Hamish Harding, my friend in sea and space." Vescovo appeared in

2703-636: Was 176 minutes; among the samples they retrieved was a piece of mantle rock from the western slope of the Mariana Trench. On June 10, 2019, Vescovo reached the bottom of the Horizon Deep in the Tonga Trench , confirming that it is the second deepest point on the planet and the deepest in the Southern Hemisphere at 10,823 m (35,509 ft). In doing so, Vescovo had descended to the first, second, and third deepest points in

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2756-598: Was a co-founder and managing partner of private equity company Insight Equity Holdings from 2000-2023. Vescovo achieved the Explorers Grand Slam by reaching the North and South Poles and climbing the Seven Summits . He visited the deepest points of all of Earth's five oceans during the Five Deeps Expedition of 2018–2019. Vescovo grew up in Dallas, Texas, where he graduated from St. Mark's School of Texas . He earned

2809-712: Was sunk during the Battle off Samar (1944) in one of the most lopsided naval battles in history. In 2022 a submersible expedition piloted by Vescovo located the wreck of destroyer escort USS  Samuel B. Roberts  (DE-413) (also sunk in the Battle off Samar in 1944), in the Philippine Sea at a depth of 6,895 metres (22,621 ft), making it the deepest wreck identified at this date. In June 2023, Vescovo lost his friend Hamish Harding , whom he had been to space and sea with, when Harding died while trying to view

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