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Distance Formula:
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The earthquake distance formula calculates the distance from the seismic station to the earthquake epicenter using the time difference between P and S wave arrivals. This method is based on the different propagation speeds of seismic waves through the Earth.
The calculator uses the distance formula:
Where:
Explanation: The formula utilizes the time difference between the faster P waves and slower S waves to estimate the distance to the earthquake epicenter.
Details: Accurate distance calculation is crucial for earthquake location determination, early warning systems, and understanding seismic hazard assessment in different regions.
Tips: Enter both P wave and S wave arrival times in seconds. Ensure S wave time is greater than P wave time. All values must be valid positive numbers.
Q1: Why is the conversion factor 8?
A: The factor 8 km/s represents the average speed difference between P and S waves in the Earth's crust, which is used to convert time difference to distance.
Q2: How accurate is this calculation method?
A: This method provides a good estimate for local and regional earthquakes, but for more precise calculations, advanced seismic analysis methods are used.
Q3: What are typical P and S wave arrival times?
A: For a magnitude 5 earthquake at 100 km distance, P waves arrive in about 20 seconds and S waves in about 35 seconds after the earthquake occurs.
Q4: Can this formula be used for deep earthquakes?
A: The formula works best for shallow crustal earthquakes. For deep focus earthquakes, more complex calculations are needed due to different wave propagation paths.
Q5: What units does the result represent?
A: The result is in kilometers, representing the straight-line distance from the seismic station to the earthquake epicenter.