Why in the News?
Portuguese scientists have predicted that the subduction zone beneath the Gibraltar Strait may lead to the Atlantic Ocean’s closure in 20 million years, reshaping the planet’s geological landscape.
- The Atlantic Ocean already has two subduction zones, the Lesser Antilles and the Scotia arcs.
- The third zone, Gibraltar Arc, is another place where a subduction zone is invading the Atlantic, although its activity is debated.
- The Gibraltar Arc System separates Nubia (NW Africa) from Iberia (SW Europe).
- The Gibraltar Strait is a 10 mile gap separating Europe and Africa, marks the meeting point of the Eurasian Plate and the African Plate.
- The African Plate is currently subducting beneath the Eurasian Plate in this region, leading to seismic events and earthquake risks.
Plate Tectonics theory:
- The Earth is made up of number of lithospheric plates (~100 km thick) those float on the hot and ductile asthenosphere.
- These plates are classified into three plate boundary types respectively, based on their movement i.e.
- Convergent Boundary (towards each other)
- Divergent Boundary (away from each other)
- Transform Boundary (slide past each other)
- The findings of the study shed light on the dynamic nature of Earth’s tectonic processes and the long-term evolution of ocean basins.
Subduction Zone
- When two plates converge towards each other, one plate which is heavier in density subducts (subducting plate) below the lighter plate (over-riding plate or stationary plate) and is consumed or destroyed in the mantle.
- The zone where subduction occurs is called the Benioff Zone.
- For e.g., 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 “Pacific 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.