why is the arrival time for the p-wave always earlier than the arrival of the s-wave the same seismograph station?
is it because the p wave always reaches before the s- wave.
Since this is not my area of expertise, I searched Google under the key words "p s wave seismograph" to get these possible sources:
http://en.wikipedia.org/wiki/Seismic_wave
http://www.seismo.unr.edu/ftp/pub/louie/class/100/seismic-waves.html
http://www.geo.mtu.edu/UPSeis/waves.html
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
I hope this helps. Thanks for asking.
Yes, you are correct. The arrival time for the P-wave is always earlier than the arrival of the S-wave at the same seismograph station. This is because the P-wave, also known as the primary wave or compressional wave, travels faster through the Earth's layers compared to the S-wave, which is the secondary wave or shear wave.
To understand why the P-wave arrives earlier, you need to consider the properties of these seismic waves. P-waves are longitudinal waves that cause particles in the ground to move in the same direction as the wave is traveling. They can travel through solids, liquids, and gases.
On the other hand, S-waves are transverse waves that cause particles to vibrate perpendicular to the direction of wave propagation. Unlike P-waves, S-waves cannot travel through liquids or gases, only through solids. This is because liquids and gases do not possess the necessary rigidity to transmit shear stress.
Since P-waves travel through all types of material, whereas S-waves do not propagate through liquids or gases, P-waves reach the seismograph station first. Once the P-wave arrives, it is followed by the S-wave.
By analyzing the time interval between the arrival of the P-wave and the S-wave at a seismograph station, scientists can calculate the distance to the earthquake source and determine its location. The larger the time difference between the P-wave and the S-wave, the further the source is from the seismograph station.