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HOW CAN WE LOCATE AN EARTHQUAKE EPICENTER
Transcript of HOW CAN WE LOCATE AN EARTHQUAKE EPICENTER
1. LOCATE AN EPICENTER BY CALCULATING ARRIVAL TIMES OF P AND S WAVES
2. UTILIZE THE ESRT TO STUDY ARRIVAL TIME CURVE
The exact location of an earthquake's epicenter and the time of the quake's occurrence are initially unknown.
All epicenter locations, as well as times of occurrence however, can be easily determined using seismograms and travel-time curves.
Look at your earth science reference table (travel times)
Suppose the separation time for the P-waves an S-waves is 3 minutes and 10 seconds.
Based on know travel times of seismic waves, the distant between the earthquake's epicenter and the seismic station that recorded the waves can only be 2000 km-no more, no less.
HOW TO FIND THE DISTANCE TO AN EARTHQUAKES YOU ARE GIVEN:
Arrival times of both the “P” and “S” waves
Lets get the arrival times for this earthquake from the next picture
So we found out by reading the seismogram that
The “P” wave arrived at: 330 seconds or
5 minutes 30 seconds
The “S” wave arrived at: 570 seconds or
9 minutes 30 seconds We then subtract the arrival time of the “P” wave and the arrival time of the “S” wave to give us the difference in arrival times.
**note you don’t have to subtract just match the arrival times on the earth science reference table chart**
So 9 minutes 30 seconds -
5 minutes 30 seconds =
On the clean edge of a sheet of paper, mark that interval along the travel-time scale on the vertical axis .Slide the marks on the edge of your paper along the “P” and “S” curves of the travel-time scale until the marks coincide with both curves. (as shown below)Follow the marked edge of your paper down to the horizontal axis to find the distance to the epicenter. (the number will be in kilometers) Our answer is 3000 km for a 4 minutes arrival time difference
If the distances between three or more seismic stations and an earthquake's epicenter are known, the exact location of the epicenter can be determined
The point at which all 3 circles intersect is the epicenter of the earthquake