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Earthquake Distance Equation:
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The earthquake distance calculation estimates how far an earthquake's epicenter is from the observation point based on the time difference between P and S wave arrivals and their velocity difference.
The calculator uses the earthquake distance equation:
Where:
Explanation: The equation calculates distance by multiplying the observed time difference between wave arrivals by the known velocity difference between the two wave types.
Details: Calculating the distance to an earthquake's epicenter is crucial for locating earthquakes, assessing potential damage, and providing early warnings to affected areas.
Tips: Enter the time difference between P and S wave arrivals in seconds and the velocity difference in km/s (default is 8 km/s). All values must be positive numbers.
Q1: What is the typical velocity difference value?
A: The average velocity difference is about 8 km/s, but it can vary slightly depending on the Earth's crust composition in different regions.
Q2: How do I measure the P-S wave time difference?
A: The time difference is measured from seismograph recordings by identifying the arrival times of the faster P waves and slower S waves.
Q3: Why does this method only give distance, not direction?
A: This calculation provides the distance but not direction. Multiple seismic stations are needed to triangulate the exact epicenter location.
Q4: How accurate is this method?
A: Accuracy depends on precise timing of wave arrivals and knowing the local velocity structure. Typically accurate within 5-10% of the actual distance.
Q5: Can this be used for deep earthquakes?
A: The method works best for shallow crustal earthquakes. For deep earthquakes, more complex calculations accounting for depth are needed.