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

Question

Infinity Learn · Accepted Answer

Suppose d $$=$$ distance of epicenter of Earth quake from point of observation vS $$=$$ Speed of $$S-wave$$ and vP $$=$$ Speed of $$P-wave$$ then $$d=vPtP=vStS$$ or $$8$$ $$tP=4.5$$ tS⇒$$tP=4.58tS$$, given that tS−$$tP=240$$ s⇒tS−$$4.58tS=240$$⇒$$tS=240$$×$$83.5=548.5$$ s∴$$d=vStS=4.5$$×$$548.5=2468.6$$≈$$2500$$ km

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