The correct option is 2 and 3 only.
Explanation
The Shadow Zone is a specific area on the Earth's surface where seismographs do not detect earthquake waves. These zones are formed due to the refraction and reflection of seismic waves as they pass through the Earth's interior, specifically interacting with the liquid outer core. The distinct behaviors of Primary (P) and Secondary (S) waves define these zones.
Statement-wise Analysis
- Statement 1 is Incorrect. The zone between 105° and 145° from the epicentre is a shadow zone for both P-waves and S-waves. In this band, neither wave is recorded. The statement claims it is a shadow zone for "only" S-waves, which implies P-waves are received there, which is factually wrong.
- Statement 2 is Correct. The shadow zone for S-waves extends continuously beyond 105° from the epicentre, covering the entire area opposite the quake. The P-wave shadow zone is restricted to the band between 105° and 145°. Therefore, the S-wave shadow zone is significantly larger (covering over 40% of the Earth's surface) than the P-wave shadow zone.
- Statement 3 is Correct. P-waves are capable of traveling through solid, liquid, and gaseous materials. They pass through the liquid outer core but are refracted, reappearing at distances beyond 145°. S-waves, however, cannot travel through liquid and are absorbed by the outer core, meaning they are never recorded beyond 105°. Thus, beyond 145°, only P-waves are recorded.
Key Takeaway
S-waves cannot travel through the liquid outer core, resulting in a massive shadow zone beyond 105°. P-waves can travel through the core but are refracted, creating a specific shadow band between 105° and 145°.