Question

Geologists use explosives to map subterranean. The time for the reflected waves to arrive at a monitoring station can tell a great deal about the composition of the rock structures. suppose the time it takes for a wave that is reflected from the interface of 1 and 2 is 2s, and the time for another wave that is reflected between 2 and 3 is 2.5s, and the speed of the wave in layer 1 is 6 km//s and in layer 2 is 4 km/s, then how thick is layer 2?

a.)1 km
b.)8 km
c.)3 km
d.)2 km
e.)6 km

Answer 1

1 km

Step-by-step explanation:

The round-trip time through layer 1 is given as 2 seconds. The total of round-trip times through layers 1 and 2 is 2.5 seconds, so the round-trip time through layer 2 is ...

2.5 s - 2.0 s = 0.5 s

Then the one-way time through layer 2 is 0.5/2 = 0.25 s. The distance traveled by the wave in that time is ...

distance = speed × time = (4 km/s)×(0.25 s) = 1.0 km

Layer 2 is 1 km thick.