From very low speed areas are under the Central pacific and theAfrica, at the top of the Earth’s outer core. In these areas, the seismic waves slow down by half and the density increases by a third. According to a new study, some of these areas are remains what shaped the Primitive earth.
The study was conducted byUniversity of Utah. According to one of the researchers, the Dr Michael Thorne, these areas would be composed ofiron oxide. If this theory turns out, this substance could influence the magnetic field terrestrial generated just below.
A seismic study that did not bear fruit …
To verify their theory, Thorne, Pachhai as well as their colleagues studied the very low speed zones under the coral sea, between Australia and New Zealand. It is an ideal location due to the abundance of earthquake In the region. Concretely, these zones provide a high resolution seismic image of the core-mantle boundary.
“The physical properties of very low velocity zones are related to their origin which, in turn, provides important information on the thermal and chemical state, evolution and dynamics of the Earth’s lowest mantle – part essential for mantle convection which drives plate tectonics. “
Dr Surya Pachhai, researcher at the University of Utah
Unfortunately, the presence of crust and mantle over 2,900 km did not help matters. Thus, scientists preferred to use a reverse engineering approach.
… but the researchers in Utah are not giving up
In fact, the two researchers wanted to know if there are internal structures, such as layers, in very low speed areas. And their model seems to confirm this.
Among their findings, the most surprising is that very low speed zones are not not homogeneous. Indeed, there are important structural and compositional variations. Even after 4.5 billion years of mantle convection, these chemicals still haven’t mixed well.
“We can create a model of the Earth that includes reductions in ultra-low wave speed and then run a computer simulation that tells us what the seismic waveforms would look like if this is what the Earth actually looked like. . “
Dr Surya Pachhai
Decidedly, the scientific community is still far from having lifted the veil on all the mysteries linked to the origin of the Earth. Even here, it was still necessary to create a model to be able to respond to their problem. As a result, the margin of error may still be high.