Indeed, according to a study published Feb. 21 in Nature Communications, the reverberations of earthquakes as they “bounce” off the core reveal new details about the structure of that core. More specifically, it increasingly reveals the presence of a second layer at the heart of what is called the inner core: something that has been suspected for twenty years, but which is not easy to “map”.
The difficulty isn’t just having devices sensitive enough to detect such distant vibrations. These echoes of an earthquake that occurs at one point on the planet bounce off another point on the opposite side of the planet and return to their point of origin, crossing the central part in a round trip that can take hours: one only The “crossing” from one point on earth to another is estimated at 20 minutes.
Researchers first had to work on distinguishing the echoes from 600 major earthquakes over the past decade, comparing how quickly their waves weaken as they traverse the core, but also distinguishing the impact that this weakening of the inner core – the solid – could have , metal part with an estimated radius of 1220 km. And once you get there, try to identify the differences within the inner core yourself, if there are any.
Therefore, one of the conclusions of the Australian seismologists in this new study is that the hypothesis of a central layer, distinct from the rest of the inner core, is confirmed, whose “transition” to the upper layer could be the “fossilized” cosmic impact that hundreds of millions of years ago or even longer.
Therefore, if they are right, we should look through textbooks and describe our planet in five layers: the crust, the mantle, the outer core, the inner core, and now the central part of the inner core.