Subduction Zone 

News Excerpt: 

A study by Portuguese scientists warns of a subduction zone, dubbed the 'Ring of Fire,' beneath the Gibraltar Strait, with the potential to engulf the Atlantic Ocean.

What is the Subduction Zone?

  • A subduction zone is a spot where two of the planet's tectonic plates collide and one dives, or subducts, beneath the other,
    • Tectonic plates are pieces of the Earth’s rigid outer layer that slowly move across the planet's surface over millions of years. 
    • This is the main tenet of plate tectonics, the theory that portions of Earth's shell glide over the lower mantle, taking continents with them.
    • That outer layer, known as the lithosphere, consists of the Earth’s crust and the upper section of the mantle, a dense, hot layer beneath the crust. 
    • When two tectonic plates meet at a subduction zone and one slides underneath the other, this lithosphere material curves down into the hot mantle.
  • This subduction process frequently occurs because of the two different types of lithosphere that make up tectonic plates: Continental and oceanic. 
    • Because oceanic material is denser than continental lithosphere, when the two collide at a subduction zone, the oceanic portion sinks into the mantle beneath the more buoyant continental lithosphere.
  • Subduction zones can also occur when both colliding plate sections consist of oceanic material. 
    • In these cases, older, denser oceanic lithosphere sinks below younger, more buoyant oceanic lithosphere. 
    • New oceanic lithosphere forms at the spots where plates separate, allowing hot mantle material to rise to the surface. 
    • As it moves away from those boundaries, this lithosphere cools and gets denser,  Thus, the older oceanic lithosphere can more easily sink.
  • The sinking plate, or "slab," at a subduction zone tends to bend at an angle of about 30 degrees from Earth's surface, though some angles are flatter or steeper than this.
  • Tectonic plate smash-ups don’t always result in a subduction zone. When two sections of continental lithosphere converge, it creates a collision zone and the plates crumple together like crashing cars, pushing up material.
    • The massive Himalaya mountain chain was created this way, when the Indian tectonic plate slammed into the Asian plate.
  • Subduction zones occur in a horseshoe shape around the edge of the Pacific Ocean, offshore of Washington state, Canada, Alaska, Russia, Japan and Indonesia and down to New Zealand and the southern edge of South America.
  • Called the "Ring of Fire," these subduction zones comprise “the most seismically and volcanically active zone in the world,” responsible for more than 80% of the world's biggest earthquakes and most of the planet’s active volcanoes.

What is Strait?

  • A strait is defined as a narrow water body bordered by landmasses that connects two larger water bodies. Straits can be formed due to the movement of tectonic plates or by the fracture of an isthmus. 

Where is the Strait of Gibraltar?

  • The Strait of Gibraltar is a narrow water passage that connects the Atlantic Ocean with the Mediterranean Sea and is also one of the world’s busiest waterways.
  • Geological studies have revealed that the Strait was formed due to the northward movement of the African Plate towards the European Plate.

Some fact about Gibraltar Strait

  • The Strait of Gibraltar is about 58 km long and has a width of about 13 km at its narrowest point between Morocco’s Point Cires and Spain’s Point Marroquí
  • The western end of the strait located between Spain’s Cape Trafalgar and Morocco’s Cape Spartel has a width of about 43 km
  • The strait’s eastern end located between the Rock of Gibraltar in the north and Mount Hacho or Jebel Moussa in the south has a width of about 23 km.
  • The Strait of Gibraltar's depth ranges from 300 to 900 m and it forms a significant gap between the high plateau of Spain and the Atlas Mountains of Northern Africa.

Book A Free Counseling Session