Earthquake Waves: Calculate Distance from Station

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SUMMARY

The discussion focuses on calculating the distance from a seismic station to an earthquake based on the arrival times of P-waves and S-waves. P-waves travel at 6.40 km/s and S-waves at 3.60 km/s. Given a time delay of 41 seconds between the two wave arrivals, the distance can be calculated using the formula for distance based on speed and time. The key takeaway is that the velocities are constant, and acceleration is not a factor in this scenario.

PREREQUISITES
  • Understanding of seismic wave types: P-waves and S-waves
  • Knowledge of basic physics concepts: speed, distance, and time
  • Familiarity with the formula for calculating distance: distance = speed × time
  • Ability to convert units of time and speed as needed
NEXT STEPS
  • Learn how to apply the distance formula in various physics problems
  • Study the properties and behaviors of seismic waves in different geological materials
  • Explore real-world applications of seismic wave analysis in earthquake detection
  • Investigate the differences between P-wave and S-wave propagation in different environments
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Students studying physics, particularly in the context of geology and seismology, as well as educators looking for practical examples of wave behavior and distance calculations.

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Homework Statement



Earthquakes produce several types of shock waves. The best known are the P-waves (P for primary or pressure) and the S-waves (S for secondary or shear). In the Earth's crust, P-waves travel at around 6.40 km/s while S-waves move at about 3.60 km/s. (The actual speeds vary with the type of material the waves are going through.) The time delay between the arrival of these two types of waves at a seismic recording station tells geologists how far away the earthquake that produced the waves occurred.

If the time delay at a seismic station is 41.0 s, how far from that station did the earthquake occur?


Homework Equations





The Attempt at a Solution



This one is really stumping me. Maybe I am missing something big. My givens are: I know two different velocities (6.4 km/h and 3.6km/h) and I know a time delay of 41 seconds. So that means that the first wave gets there 41 seconds before the second wave does. I don't really know what to do with this information. The only thing I could think of is using the formula: v^2 = v0^2 + 2a(x-x0) but since I don't know "a" I could maybe plug in (v-v0)t for "a"? I really don't know where to start. Only thing I can think of that I know I'll eventually have to do is convert 41s into .01139 hours. Can I come of with an acceleration by taking the difference of the velocities and dividing by the .01139h? Can anybody get me started? Thanks!
 
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The problem gives the velocities in km/s, and the time is in seconds, no need to convert the velocities to km/h.
The velocities are constant, there is no acceleration.

Forget about earthquakes, try to think of this more familiar problem: You and your sister start from home and go to the school. You walk with 6.4 km/h and your sister walks with 3.6 km/h. You arrive a quarter of hour earlier than your sister. How far is the school from your home?

ehild
 
Ok thanks I don't know why I converted it. Yeah thanks for the explanation; it helped.
 

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