Final answer:
The question seeks to find the origin time of an earthquake from P-wave travel time, yet lacks essential data for calculation. Normally, you would subtract the travel time from the arrival time, but the speed of the P-wave and distance to the seismic station are needed for an accurate answer.
Step-by-step explanation:
The student's question relates to determining the origin time of an earthquake based on the P-wave travel time to a seismic station. A key principle in earthquake seismology is that P-waves (primary waves) travel faster than S-waves (secondary waves), allowing seismologists to determine the distance to the epicenter by analyzing the difference in arrival times. However, the question provided does not give the needed data, such as the P-wave arrival times at multiple stations or the travel time difference between the P-wave and S-wave; instead, it asks for origin time based on a single P-wave arrival time. Without additional details, such as the speed of the P-wave or the distance from the epicenter to the station, the origin time of the earthquake can't be calculated based solely on the information provided.
To answer the actual mechanics, generally you subtract the travel time from the time of arrival to get the origin time. Since the factual details are lacking for an exact answer, a general explanation has been provided. For a complete analysis, additional data is required which includes the speed of the seismic waves and the distance from the epicenter to the seismic stations.