In the heart of the globe snowing with a hot iron, be sure the geologists. So it is possible to explain the unusual characteristics of the seismic waves that pass through the Land and Shine its like x-rays.
details of the study described in the scientific article published in the Journal of Geophysical Research: Solid Earth group, headed by Keywords by Zhang (Zhang Zhiyong) from Sichuan University, China.
the Main source of information about the center of our planet seismic waves. This kind of ultrasound scanner for earth’s interior. Thanks to him, scientists have long found that in the heart of the Earth is the solid inner core with a radius of about 1300 kilometers. It surrounds the liquid outer core with a thickness of about 2200 kilometers.
the Fruit of years of work of different research groups was the preliminary reference Earth model (preliminary reference Earth model, or PREM). It describes how depth changes the density of matter, pressure, gravity, and other parameters.
However, not so long ago, scientists got the data, contradicting the PREM. It turned out that at the bottom of the outer core seismic waves change speed slower than the model predicts. Surprise inner core through the upper part of the Eastern hemisphere wave spread faster than a similar region in the West.
Zhang and colleagues explained these data. In their opinion, the fact that in the liquid outer core partially kristallizuetsya iron.
it is Assumed that the layer precipitated on the inner core of iron has a different thickness in the Western and Eastern hemisphere.Illustration of the UT Austin Jackson School of Geosciences.
it is Curious that in the 1960s Soviet scientist Stanislav I. Braginsky suggested that between the inner and outer core of the planet there is a layer of the suspension. In the opinion of the researcher, it is solid particles of iron usweShana in the liquid. However, this theory seemed to be refuted by data on the temperature and pressure at the boundaries of the nuclei.
Zhang and colleagues conducted new experiments with materials that mimic the composition of earth’s interior, and have used published data from other groups. In addition, they drew an analogy with the well studied processes in magmatic foci of volcanoes.
Due to this, the experts came to a surprising conclusion. The bottom layer of the outer core (15% of the total thickness of the outer core) is filled with “snowflakes” of crystallized iron. This “snow” falls on the surface of the solid inner core and is going there in a kind of snow height of more than 300 kilometers.
these blockages cause an unusual change in the speed of seismic waves. The authors also suggest that the “snow” in the Western hemisphere of the inner core is thicker than in East. This explains the mysterious asymmetry.
“the border of the inner kernel is not plain and smooth surface. This may affect the thermal conductivity of the core and convection in it,” concludes Zhang.
of Course, everyone is interested to know what’s going on beneath our feet, but such research has a practical aspect. The earth’s core – the main source of the geomagnetic field that protects all life from cosmic radiation. New results are also interesting to those who are trying to understand how to shape the globe.
By the way, earlier “News.Science” (nauka.vesti.ru) wrote that at the core and the mantle found a giant tank of oxygen. We were also told when hardened inner core, and other studies heart of our planet.