Answer:
The best classification of wave mentioned in the question is longitudinal wave.
Explanation:
- If the particle displaces parallel in the direction of wave propagation then it is simply called as the longitudinal wave.
- As mentioned in the question, the particle of rock is vibrating parallel to the wave propagation i.e north south direction not top down so it is shows the nature of longitudinal wave.
- In this wave system particle do not move top down, it only oscillates back forth.
Earthquake in the bottom of the sea
There are different types of observers. Casual observers differ from scientific observer. Seeing and observing are two different things. Not that everybody seeing is actually observing the thing.
A casual observer just sits back and watch for something to happen while a scientific observer comes up with some hypothesis to work on it.