The Earth’s core is changing the shape

The internal core surface of the Earth is changing the shape, according to research published on February 10 in the magazine Nature. The research team, headed by the seismician John Vidale at the Southern University John Vidale University, reviewed the earthquake wave gliding through the core edge at a depth of 5,150 km. The analysis results are revealed even if the core turns back to the position that each previously observed, there are still extremely small changes. This proves that even in a solid form, the inner core surface may change in a short time.

“The highest possibility is the material flow in the outer core that stirres the outer surface of the inner core and changes the terrain,” Vidale said.

The outer core is molten metal, mainly iron and nickel. It surrounds the core in solid also composed largely from iron and nickel. Each year, a very small part of the core is liquid and added to the core in a solid, developing at a speed of about a millimeter per year. At the boundary between the two cores, the core is suspended right on the melting point. It is solid but not firm. That is why the core in shape changes, despite the exact size calculation of the change is a challenge. Vidale and colleagues speculated that the fluctuations could be from several hundred meters to several hundred km. In a previous study because Vidale was co -authored, he and his colleagues found that the core was not spinning at a consistent speed. It rotates faster than the rest of the planet until 2010, then starts to slow down. Currently, it rotates slower than the rest of the Earth.

Due to the inability to access or directly observe the Earth’s core, the research team uses earthquake signals to learn about the core movement. The seismic signal can move from one end of the Earth to the other, transmitted through the core in that journey. The key is to consider the earthquakes that take place at the same location. If the signal is different over the years, they may provide indirect information about the core.

This is a common technique that scientists use to learn more about speed, motion and core shape. Last year, the team analyzed more than 100 seismic signals from North America to the South Sandwich Islands in South Atlantic. Through how long the core measurement takes to turn around, they found that the core in the rotation faster and then slower than the rest of the Earth in the last few decades.

Based on that discovery, the new study considered the other side of the seismic signal between the two areas. At this time, researchers check the signal when the core is in the same position. They found them almost homogeneous but there were very small differences. They identify changes that are more likely to be associated with deformation at the inner core surface. Whether like a sphere, the core is in reality of 100 m or more at the edge of the edge.

The cause of deformation is most likely due to the force from the outer core. According to Vidale, the circulation of the liquid outer core can push the softer boundaries. Overall, the deformation in the earth does not affect the daily life of people because they are very small, according to the geologist Jessica Irving. For example, the slightly different rotation speed of the core causes extremely small changes in length a day, enough for scientists to measure but not easy to pay attention to humans.