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Sunda Trench

Oceanic trench in the Indian Ocean

Sunda Trench
Summary

Oceanic trench in the Indian Ocean

Oceanic crust is formed at the [[mid-oceanic ridge]], while the lithosphere is subducted back into the [[asthenosphere]] at trenches like that of Sunda Trench.

The Sunda Trench, earlier known as and sometimes still indicated as the Java Trench, is an oceanic trench located in the Indian Ocean near Sumatra, formed where the Australian-Capricorn plates subduct under a part of the Eurasian plate. It is 3200 km long with a maximum depth of 7,290 metres (23,920 feet). Its maximum depth is the deepest point in the Indian Ocean. The trench stretches from the Lesser Sunda Islands past Java, around the southern coast of Sumatra to the Andaman Islands, and forms the boundary between the Indo-Australian plate and Eurasian plate (more specifically, Sunda plate). The trench is considered to be part of the Alpide belt as well as one of oceanic trenches around the northern edges of the Australian plate.

Sunda Trench and the epicenters along it, due to the subduction process where the India Plate subducts under the continental fragments of the eastern microplates.

In 2005, scientists found evidence that the 2004 earthquake activity in the area of the Java Trench could lead to further catastrophic shifting within a relatively short period, perhaps less than a decade. This threat has resulted in international agreements to establish a tsunami warning system in place along the Indian Ocean coast.

Characteristics

Main article: Geology of the Sumatra Trench

For about half its length, off of Sumatra, it is divided into two parallel troughs by an underwater ridge, and much of the trench is at least partially filled with sediments. Mappings after the 2004 Indian Ocean earthquake of the plate boundary showed a resemblance to suspension bridge cables, with peaks and sags, indicative of asperity and locked faults, instead of the traditional wedge shape expected.

Exploration

Some of the earliest explorations of the trench occurred in the late 1950s when Robert L. Fisher, a research geologist at the Scripps Institution of Oceanography, investigated the trench as part of a worldwide scientific field exploration of the world's ocean floor and sub-oceanic crustal structure. Bomb-sounding, echo-train analysis, and manometer were some of the techniques used to determine the depth of the trench. The research contributed to an understanding of the subduction characteristic of the Pacific margins. Various agencies have explored the trench in the aftermath of the 2004 earthquake, and these explorations have revealed extensive changes in the ocean floor.

Crewed descent

DSSV Pressure Drop]]'' and ''DSV Limiting Factor'' at its stern

On 5 April 2019 Victor Vescovo made the first crewed descent to the deepest point of the trench in the Deep-Submergence Vehicle Limiting Factor (a Triton 36000/2 model submersible) and measured a depth of 7192 m ±13 m by direct CTD pressure measurements at 11°7'44" S, 114°56'30" E, about 500 km south of Bali. The operating area was surveyed by the support ship, the Deep Submersible Support Vessel DSSV Pressure Drop, with a Kongsberg SIMRAD EM124 multibeam echosounder system. The gathered data was donated to the GEBCO Seabed 2030 initiative. The dive was part of the Five Deeps Expedition. The objective of this expedition is to thoroughly map and visit the deepest points of all five of the world's oceans by the end of September 2019.

To resolve the debate regarding the deepest point of the Indian Ocean, the Diamantina fracture zone was surveyed by the Five Deeps Expedition in March 2019, recording a maximum water depth of 7019 m ±17 m at 33°37'52" S, 101°21'14" E for the Dordrecht Deep. This confirmed that the Sunda Trench was indeed deeper than the deepest location in the Diamantina Fracture Zone.

Associated seismicity

Main article: Sunda megathrust

The subduction of the Indo-Australian plate beneath a bloc of the Eurasian plate is associated with numerous earthquakes. Several of these earthquakes are notable for their size, associated tsunamis, and/or the number of fatalities they caused.

Sumatra segment

Java segment

References

References

  1. ''Sunda Trench'' (4°30' S 11°10' S 100°00' E 119°00' Accredited by: SCGN (Apr. 1987) The trench was studied in some detail in 1920s-1930s by Dutch geodesist F.A. Vening Meinesz, who made classic pendulum gravity measurements in a Dutch submarine. Shown as Java Trench in ACUF (Advisory Committee on Undersea Features Gazetteer). see also: http://www.gebco.net/
  2. Heather A. Stewart, Alan J. Jamieson: ''The five deeps: The location and depth of the deepest place in each of the world's oceans''. In: ''[[Earth-Science Reviews]]'' 197, October 2019, 102896, [[doi:10.1016/j.earscirev.2019.102896]].
  3. Davis, Katharine. "Asia primed for next big quake".
  4. [http://ioc3.unesco.org/indotsunami/IOC23/ioc23.htm IOC: Towards a Tsunami Warning System in the Indian Ocean] {{Webarchive. link. (1 February 2006)
  5. (2 February 2007). "Press Release: Folded sediment unusual in Sumatran tsunami area". Penn State University.
  6. (30 April 2006). "Presentation of the Drake Medal to Dr Robert L. Fisher". National Geophysical Data Center.
  7. "The underwater survey of the SUMATRA earthquake source area".
  8. Hydro International.com. (18 June 2019). "Exploring the Deepest Points on Planet Earth".
  9. Five Deeps Expedition. (16 April 2019). "Deep sea pioneermakes history again as first human to dive to the deepest point in the Indian Ocean, the Java Trench".
  10. "Nippon Foundation-GEBCO Seabed 2030 Project".
  11. (11 March 2019). "Major partnership announced between The Nippon Foundation-GEBCO Seabed 2030 Project and The Five Deeps Expedition".
  12. "Home".
  13. (2022). "High‐resolution multibeam sonar bathymetry of the deepest place in each ocean". Royal Meteorological Society.
Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

extreme-points-of-asia lowest-points-of-the-world-ocean oceanic-trenches-of-the-indian-ocean geology-of-indonesia subduction-zones
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