Answer:
(a) Since both P and S wave travels the same distance, so it can be written as: Δx = V₁t₁ = V₂t₂,
Where, V₁- Speed of S wave
V₂- Speed of P wave
t₁- time taken by S wave
t₂- time taken by P wave
Therefore, t₁ > t₂ (since, time taken by S wave is longer than P wave)
⇒ t₁ = t₂ + 1.5 min
⇒ t₁ = t₂ + 90 sec
⇒ V₁ (t₂ + 90 sec) = V₂ (t₂)
⇒ V₁t₂ + V₁ (90 sec) = V₂ (t₂)
⇒ V₂t₂ - V₁t₂ = V₁ (90 sec)
⇒ t₂ (V₂- V₁) = V₁ (90 sec)
⇒ t₂ = {V₁ (90 sec)} ÷ {(V₂- V₁)}
⇒ t₂ = {5.5 × (90 sec)} ÷ {(8.5 - 5.5)}
Therefore, t₂ = 165 sec
Since, Δx = V₁t₁ = V₂t₂
Now, Δx = V₂t₂ = (8.5 × 165 sec)
⇒ Δx = 1402 km
Therefore, Δx is approximately 1400 km (this means that the earthquake occurred at a distance of about 1400 km from the recorded seismic station)
(b) No, Only seismic station is not sufficient to detect the epicenter of an earthquake. Seismologists and geologists usually use the triangulation method in order to determine the exact location of the epicenter. This is possible by the use of three seismographs that are placed at three different locations nearby to that earthquake occurring position.
