GEOLOGY

Detailed explanation-1: -The arrival times of the P-and S-waves at different seismometers are used to determine the location of the earthquake. Assuming that we know the relative speed of P-and S-waves, the time difference between the arrivals of the P-and S-waves determines the distance the earthquake is from the seismometer.

Detailed explanation-2: -Both P and S waves travel outward from an earthquake focus inside the earth. The waves are often seen as separate arrivals recorded on seismographs at large distances from the earthquake.

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: -By measuring the time interval between the arrivals of the P and S wave groups seismologists are able to calculate the distance between the seismograph and the origin of the earthquake. Magnitude is then derived from the amplitude of the waves on the seismogram and the distance of the earthquake from the seismograph.