An earthquake occurred at 6:35:10 am. At what time did the S-wave arrive at a seismic station 4000 km away?

Answer: Around 6:55:40 Am

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