GEOLOGY

Detailed explanation-1: -If a quake is near the seismograph, the S-waves arrive shortly after the P-waves. If a quake is far from the seismograph, the P-waves arrive long before the S-waves. The longer the time is between the P-and S-wave arrivals, the further away the earthquake was from the seismograph.

Detailed explanation-2: -Finding the Distance to the Epicenter Measure the distance between the first P wave and the first S wave. In this case, the first P and S waves are 24 seconds apart. Find the point for 24 seconds on the left side of the chart of simplified S and P travel time curves and mark that point.

Detailed explanation-3: -Each seismograph records the times when the first (P waves) and second (S waves) seismic waves arrive. From that information, scientists can determine how fast the waves are traveling. Knowing this helps them calculate the distance from the epicenter to each seismograph.

Detailed explanation-4: -As the P and S waves travel out from an earthquake the P waves get progressively farther ahead of the S waves. Therefore, the farther a seismic recording station is from the earthquake epicenter the greater will be the difference in time of arrival between the P and S wave.

Detailed explanation-5: -With increasing distance from the earthquake, the time difference between the arrival of the P waves and the arrival of the S waves increases. Put more simply, the higher the time between the S and P waves (the S-P interval), the farther the distance.