SUBDUCTION ZONE (Syllabus: GS Paper 1 – Geography)

News-CRUX-10     22nd March 2024        
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Context: A recent study by scientists in Portugal predicts the 'Ring of Fire' subduction zone beneath the Gibraltar Strait may lead to the Atlantic Ocean's closure in 20 million years.


Subduction Zone

  • About: A subduction zone forms where two tectonic plates converge, leading one to descend beneath the other.
  • Nature of Tectonic Plates: Tectonic plates are segments of the Earth's outer shell that gradually shift across its surface over long periods.
  • Plate Tectonics Theory: Plate tectonics theory asserts that the Earth's shell comprises moving plates that carry continents atop the lower mantle.
  • Composition of the Lithosphere: The lithosphere, encompassing the crust and upper mantle, constitutes the Earth's outer layer.
  • Subduction Mechanism: When plates meet at a subduction zone, the denser lithosphere descends into the hot mantle, inducing curving.
  • Geological Hazards: Subduction processes yield potent earthquakes, tsunamis, and volcanic activities, marking critical geological events.
  • Lithospheric Types and Subduction: Subduction commonly arises from the interaction of contrasting lithospheric types—continental and oceanic.
  • Oceanic Plate Dynamics: Older, denser oceanic lithosphere submerges beneath younger, buoyant lithosphere, a process perpetuating subduction.
  • Formation of Oceanic Lithosphere: New oceanic lithosphere forms at plate boundaries, cooling and densifying over time, predisposing it to subduction.
  • Geographical Distribution: Subduction zones encircle the Pacific Ocean in a horseshoe shape, known as the "Ring of Fire," showcasing intense seismic and volcanic activity.

Strait of Gibraltar 

  • About: It serves as a crucial waterway, linking the Atlantic Ocean with the Mediterranean Sea and acting as the boundary between Europe and Africa.
  • Varied Depth: The depth of the Strait of Gibraltar varies considerably, ranging from 300 to 900 meters (980 to 2,950 feet; 160 to 490 fathoms), making it a complex and dynamic maritime environment.
  • Territorial Jurisdiction: The strait falls within the territorial waters of Morocco, Spain, and the British overseas territory of Gibraltar, highlighting its geopolitical significance.
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