Earthquakes produce two kinds of seismic waves: he longitudinal primary waves (called
P waves) and the transverse secondary waves
(called S waves). Both S waves and P waves
travel through Earth's crust and mantle, but
at different speeds; the P waves are always
faster than the S waves, but their exact speeds
depend on depth and location. For the pur-
pose of this exercise, we assume the P wave's
speed to be 8560 m/s while the S waves travel
at a slower speed of 5760 m/s.
If a seismic station detects a Pwave and
then 30.5 s later detects an S wave, how far
away is the earthquake center?
Answer in units of km.
Mi