Topics Covered:
- Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc., geographical features and their location- changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.
Scientists discover massive mountains under Earth’s crust
What to study?
For Prelims and Mains: Latest findings and their implications and significance, about earthquake waves.
Context: Scientists have discovered massive mountains in the Earth’s mantle, an advance that may change our understanding of how the planet was formed.
About the discovery:
- These newly discovered mountains are located between upper and lower mantle. 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.
- 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.
- Lacking a formal name for this layer, the researchers simply call it “the 660-km boundary.”
Implications:
The presence of roughness on the 660-km boundary has significant implications for understanding how our planet formed and evolved.
What are earthquake waves?
Earthquake waves are basically of two types – body waves and surface waves.
Body waves: They are generated due to the release of energy at the focus and moves in all directions traveling through the body of the earth. Hence, the name – body waves. They travel only through the interior of the earth. Body waves are faster than surface waves and hence they are the first to be detected on a seismograph. There are two types of body waves as primary waves and secondary waves.
Surface Waves: When the body waves interact with surface rocks, a new set of waves is generated called as surface waves. These waves move along the earth surface. Surface waves are also transverse waves in which particle movement is perpendicular to the wave propagation. Hence, they create crests and troughs in the material through which they pass.
Surface waves are considered to be the most damaging waves. Two common surface waves are Love waves and Rayleigh waves.
Sources: the hindu.
