The Earth’s mantle is moving ten times faster than previous estimates have suggested, says a study based on a more sophisticated method to glean underground data.
Geologists have recently discovered that the Earth’s mantle (the layer just below the crust of the planet) is moving much faster than previously thought. They came to this conclusion after mapping wave-like movements occurring inside the mantle that are called convective currents from all around the world. The motion of these currents was found to be around ten times faster than the previous theories and calculations.
The surface of the Earth is known to be always moving, very much like a yo-yo, explains the lead author of the study, geologist Mark Hoggard from Cambridge University. While we do not know the exact happenings down under, we do know that the convective activity in the mantle has a great influence on the surface of the Earth. Also, mantle convection forces the interior of tectonic plates to move up and down, says Hoggard – a phenomenon that has hitherto remained unmeasured. However, given that it is currently impossible for us to actively determine what is happening kilometres beneath our feet (the mantle is 3,000-kilometer-thick), scientists have had to rely on indirect measures to do so.
A new technique might solve this question. High-resolution seismic reflection profiles have been developed by the team to look into the Earth’s crust to measure the moving seismic waves in terms of their reflection and refraction. This data can be used to determine changes in crust thickness, and ultimately to mantle convection.
Hoggard’s team did an analysis of more than 2,000 seismic reflection measurements made from the oceans, and thus created the first global database documenting mantle convection. Their results show frequent changes in seafloor crust thickness. This suggests that the convection currents occur at a more frequent pace.
This finding is highly relevant to us. The speed at which the convective currents move inside the mantle can provide indications as to the changes of the surface of the planet, long-term climate change, and fossil fuel formation. Further explaining this, Hoggard adds that the movements down under contribute to controlling the speed at which rocks rich in organics get buried to ultimately turn into oil. Moreover, climate is thought to be affected by these motions because of their effects on ocean circulation patterns that are responsible for the distribution of heat across the globe.
Another important point is that this study can help understand why some proportion of the crust which are at a distance from plate boundaries are rising and falling when it would be more tempting to think that these regions of the crust would be more stable.