South Sandwich Trench

Map of theSouth Sandwich Plate(SAN) shows its position between theAntarctic Plate(ANT), theScotia Plate(SCO), and theSouth American Plate(SAM). TheEast Scotia Ridge(ESR), theSouth Sandwich Islands(SSI), and the South Sandwich Trench (SST) are also visible.

TheSouth Sandwich Trenchis a deeparcuatetrenchin the South Atlantic Ocean lying 100 kilometres (62 mi) to the east of theSouth Sandwich Islands.It is the deepesttrenchof the Southern Atlantic Ocean, and the second-deepest of theAtlantic Oceanafter thePuerto Rico Trench.Since the trench extends south of the60th parallel south,it also contains the deepest point in theSouthern Ocean.

The deepest point in the entire trench is the Meteor Deep, whose location prior to February 2019 was identified as55°25.12′S26°24.28′Wat a depth of 8,202 metres (26,909 ft). This sounding was made during theGerman Meteor expedition.The depth is named after theGerman 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 byVictor Vescovoas 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 subzeroHadal zonein the world.

The trench is 965 kilometres (600 mi) long and has a maximum depth of 8,266 metres (27,119 ft) below sea level at55°13.47′S26°10.23′W,as measured by a Kongsberg EM124multibeam sonarfrom February 2–7, 2019 during theFive Deeps Expedition.This measurement was made during the first complete sonar mapping of 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 thePuerto Rico Trench,sometimes known as theMilwaukee or Brownson Deep.

The trench is produced by thesubductionof the southernmost portion of theSouth American Platebeneath the smallSouth Sandwich Plate.The South Sandwich Islands constitute avolcanicisland arcwhich results from this active subduction.Mount BelindaonMontagu Islandis an activevolcano.

Meteor Deep 2019 survey

DSSV Pressure DropandDSV Limiting Factorat its stern

In February 2019, however, the Five Deeps Expedition, led by its survey shipDSSVPressure Drop,has recommended that the location of the Meteor Deep be "relocated" to the newly discovered, truly deepest location at55°13.47′S26°10.23′Wand 8,266 metres (27,119 ft) ± 13 metres (43 ft) in depth, given 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 Dropcompleted an entire survey of the trench on February 9, 2019, and made the data publicly available toGEBCOin 2019. Approximately ten other major subsurface features including various deeps, seamounts, and ridges—previously unidentified—were mapped by the vessel and new names for the features were submitted to theInternational Hydrographic Organization(IHO) in 2019.

"Factorian Deep" crewed descent

The southernmost portion of the South Sandwich Trench reaches south of 60°S latitude and is therefore in theSouthern 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 the deepest point at60°28.46′S025°32.32′W,with a depth of 7,434 metres (24,390 ft) ± 13 metres (43 ft). The expedition leader and chief submersible pilotVictor Vescovohas proposed naming this deepest point in the Southern Ocean the "Factorian Deep," based on the name of the crewed submersible DSVLimiting Factor,in which he successfully visited 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.

See also

• Antarctica
• Scotia Sea

References

• Structural evolution of the Scotia Sea floor during paleogene-quaternary period (West Antarctic)
• "South Sandwich Islands, southern Atlantic Ocean".Volcano World.Oregon State University. Archived fromthe originalon 10 July 2008.Retrieved19 November2013.
• Patrick, Matthew R.; Smellie, John L.; Harris, Andrew J. L.; Wright, Robert; Dean, Ken; Izbekov, Pavel; Garbeil, Harold; Pilger, Eric (2004). "First recorded eruption of Mount Belinda volcano (Montagu Island), South Sandwich Islands".Bulletin of Volcanology.67(5): 415–422.doi:10.1007/s00445-004-0382-6.S2CID54187857.