Primary waves (P-waves) are the fastest seismic waves while Secondary waves (S-waves) are slower and reach the seismograph second.
Primary waves (P-waves) are the fastest seismic waves, traveling through the Earth at about 6 to 7 kilometers per second. They are the first waves to reach a seismograph due to their high speed. In comparison, Secondary waves (S-waves) are slower, moving at about 3.5 kilometers per second and are the second waves to reach a seismograph.
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