Assume a distance from epicenter to seismograph of 100 km.Otherwise, there is no

Question

Assume a distance from epicenter to seismograph of 100 km.Otherwise,

there is not enough information to answer the question.

(a) Seismographs measure the arrival times of earthquakes with a
precision of 0.100 s. To get the distance to the epicenter of the quake,
they compare the arrival times of S- and P-waves, which travel at
different speeds. Figure 16.48) If S- and P-waves travel at 4.00 and 7.20
km/s, respectively, in the region considered, how precisely can the
distance to the source of the earthquake be determined? (b) Seismic
waves from underground detonations of nuclear bombs can be used to
locate the test site and detect violations of test bans. Discuss whether
your answer to (a) implies a serious limit to such detection. (Note also
that the uncertainty is greater if there is an uncertainty in the propagation

Explanation / Answer

distance = d = 100 km

speed of s-waves = 4 km/s

speed of p waves = 7.2 km/s

speed of P-waves relative to s-waves = 7.2 km/s - 4 km/s = 3.2 km/s

uncertainty in time = 0.1 sec

uncertainty in distance = speed x uncertainty in time = 3.2 x 0.1 = 0.32 km

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.