Earthquake Epicenter Calculator

'Earth is shaking'

Monty >> "OMG AN EARTHQUAKE"

You >> "Duck!!"

'House crashes down'

Monty >> "Where on earth did that come from?"

You >> "I don't know yet Monty, but we'd better find out."

'Synchronous evil laughter'

First, let's determine how far away the earthquake was.

1. Obtain P- and S-wave arrival times from three locations.
2. Calculate the difference between P- and S-wave arrival times at each location (seconds).
3. Use the difference in arrival time to determine distance (in km) from the earthquake at each location.

Let's also determine the earthquake's magnitude (Richter scale):

4. Determine the amplitude of the strongest wave (mm).
5. Use the difference in arrival time and the amplitude to determine the magnitude of the earthquake.

Now, let's locate the epicenter:

6. Draw radius around each location using the distance found in 3.
7. Determine where the 3 circles intersect.

reminder, GPS N and E are +, S and W are negative(-)

Advanced option: write program that analyzes the seismograms for you. determines p- and s-wave arrival times and amplitude of strongest wave.

Formula Variables

event = (p-arrival-time, s-arrival-time, max_amp)
station = ('location', coords)
coords = (lat, lon)  # lat, lon in degrees

other variable key:

d = distance to earthquake
tS = S-wave arrival time
tP = P-wave ""
vS = velocity of S-wave
vP = velocity of p-wave

d = (tS-tP/(1/vS-1/vP)