Sagot :
Primary waves (P-waves) are compressional waves that are longitudinal in nature. P-waves are pressure waves that travel faster than other waves through the earth to arrive at seismograph stations first, hence the name "Primary".

Primary waves (P-waves) are compressional waves that are longitudinal in nature. P-waves are pressure waves that travel faster than other waves through the earth to arrive at seismograph stations first, hence the name "Primary".