Answer: Around 6:55:40 Am
Step-by-step explanation:
The velocity of the S wave may depend on the density of the ground.
The speed can go from 1km/s to 8km/s, with an average velocity of 3.25km/s
Now, we can use the equation:
Velocity = distance/time.
Time = distance/velocity.
We have distance = 4000km
and velocity = 3.25km/s
time = 4000km/3.25km/s = 1230.77 seconds.
now, a minute has 60 seconds, so this is:
1230.77/60 = 20.5 minutes. or 20 minutes and 30 seconds
So the earthquake will reach the seismic station around
6:35:10 + 0:20:30 Am
6:55:40 Am