By using the time differences in the arrivals of P-waves and S-waves at the St. Louis and Houston seismic stations, a geologist can employ triangulation to determine the location of the earthquake's epicenter.
Triangulation relies on the time it takes for seismic waves to travel from the earthquake's epicenter to different recording stations. This time differences method relies on the principle that seismic waves travel at known speeds through the Earth's interior and that the epicenter is equidistant from the recording stations where the waves are detected.
To determine the location of the earthquake epicenter with only seismic data from stations in St. Louis and Houston, a geologist can use a method known as triangulation.
The process are as follows:
1. Calculate the time difference: The geologist would first calculate the time difference between when the earthquake's P-waves (primary waves) and S-waves (secondary waves) arrived at both the St. Louis and Houston stations.
2. Draw circles on a map: Using the calculated time differences and the known seismic wave speeds in the Earth's crust, the geologist would draw circles on a map around each seismic station, with the station itself at the center of each circle.
3. Find the intersection: The epicenter of the earthquake would be located at the point where the circles drawn around St. Louis and Houston intersect. This is because the actual epicenter is equidistant from both stations and the intersection of the circles represents that common distance.