• Scientists have discovered massive mountains in the Earth’s mantle, an advance that may change our understanding of how the planet was formed.
  • Most school children 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.

Tell us more about the Earthquake data

  • In a study published in the journal Science, 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 send out shockwaves in all directions that can travel through the core to the other side of the planet — and back again.
  • Scientists used powerful computers to simulate the complicated behaviour of scattering waves in the deep Earth.
  • The technology depends on a fundamental property of waves: their ability to bend and bounce.
  • Just as light waves can bounce (reflect) off a mirror or bend (refract) when passing through a prism, earthquake waves travel straight through homogenous rocks but reflect or refract when they encounter any boundary or roughness.
  • The researchers were surprised by just how rough that boundary is — rougher than the surface layer that we all live on.
  • In other words, stronger topography than the Rocky Mountains or the Appalachians is present at the 660-km boundary.
  • The roughness was not equally distributed, either; just as the crust’s surface has smooth ocean floors and massive mountains, the 660-km boundary has rough areas and smooth patches.
  • The researchers also 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.