TheSunda Trench, earlier known as and sometimes still indicated as theJava Trench,[1] is anoceanic trench located in theIndian Ocean nearSumatra, formed where theAustralian-Capricorn plates subduct under a part of the Eurasian plate. It is 3,200 kilometres (2,000 mi) long with a maximum depth of 7,290 metres (23,920 feet).[2] Its maximum depth is the deepest point in theIndian Ocean. The trench stretches from theLesser Sunda Islands pastJava, around the southern coast ofSumatra to theAndaman Islands, and forms the boundary betweenthe Indo-Australian plate andEurasian plate (more specifically,Sunda plate). The trench is considered to be part of theAlpide belt as well as one ofoceanic trenches around the northern edges of theAustralian plate.
In 2005, scientists foundevidence that the 2004earthquake activity in the area of the Java Trench could lead to further catastrophic shifting within a relatively short period, perhaps less than a decade.[3] This threat has resulted in international agreements to establish atsunami warning system in place along theIndian Ocean coast.[4]
For about half its length, off ofSumatra, 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 the2004 Indian Ocean earthquake of the plate boundary showed a resemblance tosuspension bridge cables, with peaks and sags, indicative ofasperity and locked faults, instead of the traditional wedge shape expected.[5]
Some of the earliest explorations of the trench occurred in the late 1950s when Robert L. Fisher, a research geologist at theScripps 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.[6] Various agencies have explored the trench in the aftermath of the 2004 earthquake, and these explorations have revealed extensive changes in the ocean floor.[7]
On 5 April 2019Victor Vescovo made the first crewed descent to the deepest point of the trench in the Deep-Submergence VehicleLimiting Factor (a Triton 36000/2 model submersible) and measured a depth of 7,192 m (23,596 ft) ±13 m (43 ft) by directCTD pressure measurements at 11°7'44" S, 114°56'30" E,[8][9] about 500 km (310 miles) south ofBali. The operating area was surveyed by the support ship, the Deep Submersible Support VesselDSSV Pressure Drop, with a Kongsberg SIMRAD EM124 multibeam echosounder system. The gathered data was donated to theGEBCO Seabed 2030 initiative.[10][11] The dive was part of theFive 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.[12]
To resolve the debate regarding the deepest point of the Indian Ocean, theDiamantina fracture zone was surveyed by the Five Deeps Expedition in March 2019, recording a maximum water depth of 7,019 m (23,028 ft) ±17 m (56 ft) at 33°37'52" S, 101°21'14" E for theDordrecht Deep.[8] This confirmed that the Sunda Trench was indeed deeper than the deepest location in the Diamantina Fracture Zone.[13]
Thesubduction of theIndo-Australian plate beneath a bloc of theEurasian 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.
10°19′S109°58′E / 10.317°S 109.967°E /-10.317; 109.967
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