Earth’s Outer Core Is Changing Based on Seismic Waves From Earthquakes, Study Claims

A recent analysis of seismic waves propagating from two distinct earthquakes has shown changes that are taking place in Earth's mantle and the inner core and outer core.

The magnetic field of our planet is directly influenced by the outer core and the iron it contains and is thereby shielded from solar and cosmic radiation that would otherwise make life on Earth impossible.

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Seismic Wave Speed Points Explained

Author Ying Zhou of the Virginia Tech College of Science's Department of Geosciences looked at rapid fluid movement in the outer core by examining the so-called transient change in "seismic wave speed points" in the research.

According to Zhou, the researchers' critical and first-ever look at what's going further into the Earth's center, in its outer core, is made possible by a one-second difference in the SKS wave travel time.

The majority of the outer core's composition may not be pure iron, according to observations and findings of the seismic waves' speed and density from the aforementioned earthquakes. Instead, it may also contain light elements like silicon, hydrogen, carbon, oxygen, nitrogen, and light forms of nitrogen and oxygen.

Analysis of the SKS waves and their reference waves between 1990 and 2019 was the primary method used to make the finding. The study was published in the journal Communications Earth & Environment on April 25.

Here's What's Inside Earth's Inner Core, Mantle

The inner core, the planet's deepest internal layer, and the mantle, the thick layer of rock beneath the surface of the Earth, are sandwiched between the outer core. It is mostly made of liquid iron that flows or convects when the Earth cools. The resultant spinning of the liquid metal creates electrical currents that form the Earth's magnetic field, shielding the planet and all life inside it from dangerous solar winds and radiation.

The Earth couldn't support life without its magnetic field, and the magnetic field wouldn't function without the flowing liquid metal in the outer core. Simulations, however, are the foundation of science's knowledge of this dynamic, according to assistant professor Zhou.

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"If you look at the north geomagnetic pole, it's currently moving at a speed of about 50 kilometers [31 miles] per year," Zhou said per Virginia Tech. "It's moving away from Canada and toward Siberia. The magnetic field is not the same every day."

Additionally, scientists have only been able to make educated guesses about the cause of the gradually observed variations in the magnetic field's intensity and direction, which most likely entail shifting flows in the outer core.

Although Zhou said that the alterations in the outer core are not spectacular, they are nonetheless important to check and fully comprehend. The scientists identified a "direct sampling" method of the outer core in seismic waves and their variations in speed across timescales of ten years. It is a result of the SKS waves she analyzed directly passing through it.

Seismic Wave, Earth's Core Explained

Seismic waves, also called compressional or longitudinal waves, are "elastic waves" because they are created by powerful geological impulses like earthquakes or explosions.

The United States Geological Survey (USGS) mentioned that the seismic energy might move along or close to the Earth's surface in addition to moving within.

According to the USGS, waves that move across the planet's surface are referred to as "Rayleigh and Love waves," while waves that go within its interior are referred to as "P and S waves."

The inside of our planet, also known as the Earth's core, is described by the National Geographic Society as an "extremely hot" and "very dense" area. Below the crust and mantle, which are all components of the planetary layers, lies the core, which is likened to the form of a ball.

The core's radius is roughly 2,165 miles and is located around 1,802 miles (2,900 kilometers) beneath the surface (3,485 kilometers). Most significantly, the core rotates independently and continuously, and it is via this movement the Earth's magnetic field is created.