# Seismic Waves: Mapping the Interior of the Earth

Seismic waves are waves of energy that travel through the Earth’s layers and are a result of earthquakes, volcanic eruptions, massive landslides and large human-made explosions. Some types of seismic waves travel through the interior of the Earth and are detected by seismic stations on the other side of the Earth. By analyzing the types of waves that are received by seismic stations, we can determine the interior of the Earth.

Flat-Earthers are often seen saying that it is impossible to determine the interior of the Earth as nobody has gone there. They are wrong. Using seismology, we can determine the interior of the Earth without going there physically.

There are several types of seismic waves. The types that travel through the interior of the Earth are P-waves (primary) and S-waves (secondary).

P-waves are longitudinal waves (the displacement of the medium is in the same axis as the direction of propagation). These waves travel faster than other waves and can move through any material, including fluids.

S-waves are traverse waves (the displacement of the medium is perpendicular to the direction of propagation). S-waves are slower than P-waves, and cannot penetrate all types of material as easily as P-waves.

When an earthquake happens, it will generate P-waves and S-waves. Depending on the location of a seismic station all over the surface of the Earth, it will detect both types of waves,  only P-waves, or nothing. From the kind of waves that are received by many seismic stations all over the world, we can determine the interior of the Earth.

Flat-Earthers are often seen repeatably stating that the deepest borehole we can drill through the crust of the Earth is only 12 km (8 miles) deep. They would conclude from the fact that it is impossible to determine the interior of the Earth. They are wrong. Using our knowledge of seismology, we can identify what lies inside the interior of the Earth. Just because they are unable to understand seismology, it doesn’t mean seismology is wrong.