Answer:
1. the vibration starts picking up getting stronger and stronger causing the tectonic plate to shake more vigorously
(c) Surface waves
Explanation:
P waves - labelled as (a) on the graph - travel fastest and are the first to arrive from the earthquake. In S - labelled as (b) - or shear waves, rock oscillates perpendicular to the direction of wave propagation. In rock, S waves generally travel about 60% the speed of P waves, and the S wave always arrives after the P wave
