An earthquake has just occurred. Seismic waves from the earthquake are detected at two recording stations. At Recording Station $A$, $\Delta T=45 s$. At Recording Station $B$, $\Delta T=100 s$. Which recording station is farther away from the epicenter?
A. $A$ is farther from the epicenter than $B$.
B. $B$ is farther from the epicenter than $A$.
C. $A$ and $B$ are the same distance from the epicenter.
D. Cannot be determined.

The difference in arrival time of seismic waves is proportional to the distance from the epicenter. Since Recording Station B has a larger difference in arrival time (100 s) than Recording Station A (45 s), Recording Station B is farther from the epicenter. Therefore, the answer is: B is farther from the epicenter than A.
Explanation

Understanding the Problem We are given the difference in arrival times of seismic waves at two recording stations, A and B. We know that the difference in arrival time ( Δ T ) is related to the distance from the epicenter. The larger the difference in arrival time, the farther the recording station is from the epicenter.

Comparing Arrival Times At Recording Station A, Δ T A ​ = 45 seconds. At Recording Station B, Δ T B ​ = 100 seconds. Since \Delta T_A"> Δ T B ​ > Δ T A ​ , Recording Station B is farther away from the epicenter than Recording Station A.

Conclusion Therefore, Recording Station B is farther away from the epicenter.


Examples
Imagine you are tracking a thunderstorm using lightning strikes. The farther you are from the storm, the longer it takes to hear the thunder after seeing the lightning. If you hear the thunder 5 seconds after seeing the lightning, and your friend hears it 10 seconds after seeing the lightning, your friend is farther away from the thunderstorm. This principle is similar to how seismologists determine the distance to an earthquake's epicenter using the arrival times of seismic waves.

Answered by GinnyAnswer | 2025-07-08

The recording station farther from the epicenter is B, as it has a greater difference in arrival time (100 seconds) compared to station A (45 seconds).
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Answered by Anonymous | 2025-07-27