Answer
a. 9:1
b. 3:1
Work Step by Step
a. Assume that the earthquake waves are spherical waves, as discussed in section 11-9. Intensity is inversely proportional to the square of the distance from the wave source. The second point is 3 times farther from the source than the first location, so the intensity is 1/9 as much.
b. The amplitude is inversely proportional to the distance from the wave source, so the amplitude at 45 km is 1/3 as much as it is at 15 km.
