* P-Waves and S-Waves: Earthquakes generate two main types of seismic waves:

* P-waves (Primary waves): These are compressional waves that travel faster through the Earth.

* S-waves (Secondary waves): These are shear waves that travel slower than P-waves and cannot travel through liquids.

* Earth's Core: The Earth's core is mostly liquid iron.

* Shadow Zone: Because S-waves can't travel through the liquid outer core, there's a region on the opposite side of the Earth from an earthquake where no S-waves are recorded. This is part of the shadow zone.

* P-Wave Refraction: P-waves can travel through the liquid core, but they are refracted (bent) as they pass from the mantle into the core. This refraction causes a zone where P-waves are also not directly recorded. This is the other part of the shadow zone.

The shadow zone is a region approximately 103 to 142 degrees away from the epicenter of an earthquake. This is where you would find no direct recordings of either P-waves or S-waves.

Important Note: While the shadow zone is a very useful tool for understanding Earth's structure, there might be some weak P-waves recorded in this region due to scattering and reflections.