Earth's Interior
The Kola Superdeep Borehole, the deepest hole ever drilled on Earth, is only over 7.6 miles, a mere fraction of Earth’s total depth.
Since digging very deep is impossible, how do scientists learn about Earth’s interior? Let’s see.
One key method involves studying seismic waves produced during an earthquake. These waves are of two types: primary and secondary.
Primary waves, or P waves, travel faster in dense rocks and slower in fluids. Their speed and direction change as they travel between different layers.
On the other hand, secondary waves, or S waves, travel only through solids and do not pass through liquids.
Since P waves slowed down when they reached the outer core, and S waves stopped completely, scientists inferred that the outer core is liquid.
By analyzing these waves, scientists mapped out Earth’s layers, the crust, the mantle, and the core.
Another clue is Earth’s density. Since the planet’s overall density is higher than that of the crust alone, it indicates the presence of a dense metallic core.
The Kola Superdeep Borehole, the deepest hole ever drilled on Earth, is only over 7.6 miles, a mere fraction of Earth’s total depth.
Since digging very deep is impossible, how do scientists learn about Earth’s interior? Let’s see.
One key method involves studying seismic waves produced during an earthquake. These waves are of two types: primary and secondary.
Primary waves, or P waves, travel faster in dense rocks and slower in fluids. Their speed and direction change as they travel between different layers.
On the other hand, secondary waves, or S waves, travel only through solids and do not pass through liquids.
Since P waves slowed down when they reached the outer core, and S waves stopped completely, scientists inferred that the outer core is liquid.
By analyzing these waves, scientists mapped out Earth’s layers, the crust, the mantle, and the core.
Another clue is Earth’s density. Since the planet’s overall density is higher than that of the crust alone, it indicates the presence of a dense metallic core.
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