Question

1. why do some stations only receive p-waves and some receive no waves? earthquake epicenter p- and s- waves p- and s- waves 102° shadow zone, no waves 102° shadow zone, no waves 143° 143° p-waves only

Explanation:

This is related to the Earth's interior structure and seismic wave behavior. P - waves (primary waves) can travel through solids, liquids, and gases, while S - waves (secondary waves) can only travel through solids. The Earth has a liquid outer core. When seismic waves from an earthquake reach the liquid outer core, S - waves are refracted (or cannot pass through the liquid) and P - waves are refracted. Stations in the "P - waves only" zone (between 102° and 143° from the epicenter) receive P - waves because P - waves can bend (refract) when entering the liquid outer core and reach these stations, but S - waves can't pass through the liquid outer core to reach them. Stations in the "shadow zone" (beyond 143° from the epicenter) receive no waves because the refraction of P - waves and the inability of S - waves to pass through the liquid outer core create a region where seismic waves don't reach.

Answer:

This is due to the Earth's interior structure (liquid outer core) and seismic wave properties:

• P - waves only zone (102°–143° from epicenter): P - waves (can travel through liquids/solids) refract at the liquid outer core and reach these stations, but S - waves (only travel through solids) cannot pass through the liquid outer core to reach them.
• Shadow zone (>143° from epicenter): Refraction of P - waves and S - waves’ inability to pass through the liquid outer core create a region where no seismic waves reach.