An earthquake generates both transverse (S) and longitudinal (P) sound waves in the earth. The speed of S waves is about 4.5 km /s and that of P waves is about 8.0 km/s . A seismograph records P and S waves from an earthquake. The first P wave arrives 4.0 min before the first S wave. The epicenter of the earthquake is located at a distance about

Options

A. 25 km
B. 250 km
C. 2500 km
D. 5000 km

Answer

C

Explanation

IF x be the distance of epicentre from the seismograph, then
`x/v_s-x/v_p=4 times 60 or x/4.5-x/8=4 times 60`
on simplifying, we get
x=2500 km