Question

question 3
what are the first waves to arrive at a gauging station?
primary waves
secondary waves
surface wave
none of the above

question 4
the elastic rebound theory explains the occurence of earthqaukes.
true
false

question 5

Explanation:

• Question 3: Primary waves (P - waves) are compressional waves. They travel fastest among seismic waves (faster than secondary waves (S - waves) which are shear waves and surface waves which are slower). So, they are the first to arrive at a gauging station.
• Question 4: The elastic rebound theory, proposed by H.F. Reid, explains that when rocks on either side of a fault are subjected to stress and deform, they store elastic energy. When the stress exceeds the strength of the rocks, the rocks break (faulting occurs) and the stored elastic energy is released as seismic waves, causing an earthquake.

Answer:

• Question 3: Primary waves
• Question 4: True