ZAGREB, October 28, 2018 – Croatian-born Australian geophysicist Hrvoje Tkalčić has confirmed the 80-year-old hypothesis that Earth’s inner core is made of solid material and said that the Earth’s correlation field method, which has helped his group make that discovery, brings a new paradigm to science.
Tkalčić has co-authored a paper with Thanh-Son Pham, published in a recent issue of Science magazine, which has elicited interest among experts and which colleagues say has implications for understanding the composition of Earth’s inner core.
We have managed to generally prove that Earth’s inner core is in a solid state of aggregation, which hypothesis was set about 80 years ago. It hasn’t been proved until now, although the clues were quite strong, Tkalčić has told Hina.
He says his team was able to prove that by detecting shear winds in Earth’s inner core, a direct proof of that. Those waves can move only in solid objects, not through liquid or gas, he adds. Using a global network of stations, we paired every receiver and every major earthquake, measuring the similarities between seismograms, Tkalčić says, adding that the number of combinations was large. He says they used those similarities to make a global correlogram, a sort of fingerprint of the Earth.
Tkalčić was born in Bjelovar in 1970 and obtained a degree in geophysics at the Zagreb Faculty of Science in 1996. He has also discovered that Earth’s inner core is softer than previously thought.
Aside from detecting those waves, we have managed to measure the speed of their expansion, from which you can then determine other physical or chemical parametres of a material. In this case, we have determined that the behaviour of the material making up Earth’s inner core is more similar to some other chemical elements than to iron under normal temperatures and pressures, Tkalčić says.
This is another piece of good news for Croatian science, after it was recently announced that Croatia will enter the CERN in 2019.