Question

question the seismograph below records the arrival times of seismic waves at a station in portland. portland seismograph image showing lag - time from 0 to 200 s lag time (s) using the seismograph data provided, which of the following correctly identify the arrival times for the p and s waves? a the p wave arrives at 120 seconds and the s wave arrives at 240 seconds. b the p wave arrives at 0 seconds, and the s waves arrives at 60 seconds. c the p wave arrives at 0 seconds, and the s wave arrives at 120 seconds. d the p wave arrives at 60 seconds, and the s wave arrives at 180 seconds.

Explanation:

Step1: Identify P - wave arrival

P - waves are the first to arrive. Looking at the seismograph, the first set of vibrations is at 0 seconds, which is the arrival time of the P - wave.

Step2: Identify S - wave arrival

S - waves arrive after P - waves. The second set of vibrations on the seismograph is at 120 seconds, which is the arrival time of the S - wave.

Answer:

C. The P wave arrives at 0 seconds, and the S wave arrives at 120 seconds.