What is going on? One idea is that two giant powers are fighting for control of the world’s core. Earth’s magnetic field, generated by eddy currents of iron in the molten outer core, tugs on the inner core, causing it to spin. This thrust is countered by the mantle, the layer of mucus above the outer core and beneath the Earth’s crust, by the immense gravitational field that holds the inner core and slows its rotation.
By studying the basis of recorded subduction seismic waves from the 1960s to the present day, Dr. Song Wei Yang, another seismologist at Peking University and one of the authors of the study, thinks that this massive tug of war causes the inner core to rotate backwards. And back and forth in a cycle of about 70 years.
In the early 1970s, for a person standing on the surface of the earth, the inner core did not rotate. Since then, the inner core has gradually rotated faster and faster eastward, eventually surpassing the rotational speed of the Earth’s surface. After that, internal core rotation slowed to an apparent halt at some point between 2009 and 2011.
The inner core is now gradually rotating westward relative to the Earth’s surface. It will likely speed up and then slow down again, stopping again in the 40s and completing its latest east-west loop.
This 70 year rhythm, if at all, could have a measurable impact on this part of the Earth. deeper intestine. But they may only be able to provoke relatively small disturbances near the surface – perhaps by causing slight shifts in the planet’s magnetic field, or even by slightly tweaking the length of the day, which is known to increase and decrease by milliseconds. every six years.
It is just one of several competing models that explain the passage of irregular waves to the core. There may also be deeper layers of the earth tossed around. In contrast, the Earth’s iron core may have a shifting surface, which causes the seismic waves that penetrate it to bend. “No matter which model you like, there are some data points you don’t agree with,” says Dr. Vidal.
Due to the inaccessibility of this Immortal Realm, he might escape interpretation forever. “It’s very likely that we’ll never know,” says Dr. Vidal. But he added: “I’m optimistic. The pieces will fall into place one day.”
