Scientists have discovered large and mysterious structures made of material possibly dating back to an era before the Earth had a moon deep underground between the Earth’s liquid outer core and the lower mantle, according to a paper published in the Science magazine on Thursday.
Referred to as ultra low velocity zones (ULVZs), all that scientists know for sure about these underground structures is that their diameters are about 100 kilometres and they are dense enough to slow waves that pass through them. Scientists theorize that they may be composed of exotic, partially-melted materials from an age when the Earth didn’t even have a Moon, which is believed to have been formed due to a major collision over four billion years ago between an early Earth and a large object around the size of Mars.
The team of scientists, led by Doyeon Kim, fed seismograms, which are essentially records of the tremors caused by earthquakes, into an algorithm called Sequencer, which allowed them to measure 7,000 measurements of earthquakes. This allowed them to study more or less the entire Pacific basin and allows them to map out structures deep inside the Earth’s unknown and unexplored underworld. Kim explained they are trying to bring together diverse datasets in order to look for these underground structures in a systematic manner and understand their finer details.