Mains Paper 1: Geography | Changes in critical geographical features
From the UPSC perspective, the following things are important:
Prelims level: Interior of Earth
Mains level: Structure and feature of Earth’s interior
- Scientists have discovered massive mountains in the Earth’s mantle, an advance that may change our understanding of how the planet was formed.
Earth’s Interior is different
- We often learn that the Earth has three layers: a crust, mantle and core, which is subdivided into an inner and outer core.
- While that is not wrong, it does leave out several other layers that scientists have identified within the Earth.
Earthquake data helps study
- In a study published in the journal, scientists used data from an enormous earthquake in Bolivia to find mountains and other topography on a layer located 660 km straight down, which separates the upper and lower mantle.
- Lacking a formal name for this layer, the researchers simply call it “the 660-km boundary.”
- Data from earthquakes that are magnitude 7.0 or higher sends shockwaves in all directions that can travel through the core to the other side of the planet — and back again.
The transition zone
- The key data came from waves picked up after a magnitude 8.2 earthquake — the second-largest deep earthquake ever recorded — that shook Bolivia in 1994.
- The researchers examined a layer 410 km down, at the top of the mid-mantle “transition zone,” and they did not find similar roughness.
- The presence of roughness on the 660-km boundary has significant implications for understanding how our planet formed and evolved.