Because P and S waves travel at different but fairly constant speeds, the interval between their arrivals increases in proportion to the distance from the earthquake focus, or initial rupture point.
由于 P 波和 S 波以不同但相当恒定的速度传播，它们到达的间隔与到震源或初始破裂点的距离成比例地增加。
2
With the measured P and S wave velocities and log-derived densities of the same interval, rock mechanical parameters of this pre-borehole are roughly calculated.