Question

An earthquake emits both S-waves and P-waves which travel at different speeds through the Earth. A P-wave travels at 9000 m/s and an S-wave travels at 5000 m/s. If P-waves are received at a seismic station 2.00 minute before an S wave arrives, how far away is the earthquake center?

Answer 1

the distance is 1350 Km

Step-by-step explanation:

To solve this problem we will use the formulas of contant velocity motion:

`d=v*t\\where:\\d=distance\\v=velocity\\t=time`

Because the waves have to travel the same distance we can set the following equallity:

`vs*ts=vp*tp`

We know that the s waves arrive 2 minutes later, that is 120 seconds:

`vs*(120+t1)=vp*t1`

Rearranging the last equation we have :

`t1=120*(vs)/(vp-vs)\\\\t1=120*(5000)/(9000-5000)\\\\t1=150seconds`

As we said before they have to travel the same distance, so:

`d=9000((m)/(s))*150(s)\\d=1350000(m)\\d=1350(km)`