It could be practically anything, Scholte wave, Rayleigh waves, leaky Rayleigh wave, etc...It depends on the system you are studying.

I enclose a paper which shows a couple of the possibilities for the ocean bottom environment.

It is unlikely to be noise, as the waveform is very clear, and around 14Hz you have a lot of continuous ambient noise.

Hello Martin, the frequency 14Hz does not belong to the wave.It is the frequency of geophone. The frequency of the wave varies between 1-3 KHz.

Ah? Could you elaborate on the 14Hz is that the sampling rate or what exactly? I do not understand how the wave can be between 1-3KHz and your geophone at 14Hz.

Martin,14 Hz is the natural frequency of geophone here and it can record waves up to 2 KHz.I have sent you the geophone detail.

Dear Vikalp,

by thecharacteristic of the geophone it seems you are acquiring data either in a borehole or in a laboratory, not standard surface seismology. What is the geometry of the sensors? I see there is a distance (from what?) from 2 m to 129 m.

Are you sampling correctly the data? I mean, to exploit the 2 kHz band of the geophone the recording system must sample at frequency greater than 4 kHz (maybe the 6 kHz value in the figure).

Are all the stations tri-axial? Because NTPC22 and NTPC16 have signals only on the third component.

The signals on NTPC12, NTPC13, NTPC17 don't seem to belong to body waves (P & S) because there is no difference in arrival times on the 3 traces.

Did you try to plot the traces together ordered by distance? It should help to see the moveout and to derive velocity value.

Regards,

Lorenzo

Hello Lorenzo I am acquiring data in a powerhouse cavern,sensors are installed at a depth of  around 10-30m from the surface at different lcations in the transformer and machine hall.Few stations are tri and few are uni.I want to know what type of signal  it is which i received. 

Dear Vikalp,

I have very few information: a plot with the position of the sensors and the distances could help. Are the arrival times those written at the right of the station name?

With such few info I can do only some hypothesis.

Anyway, from the plot of the signals I see the parameter "lenght". If it is the lenght of the wavelet, the dominant frequency would be 50-67 Hz, except for NTPC13 which is 125 Hz. So, because you are in a powerhouse it comes in my mynd some kind of electrical related noise (spikes) and NTPC13 could be the 2nd harmonic.

Regards,

Lorenzo

It looks like you system is supplied by IMS. Check with them and they advise you. Ensure there are no electrical signal in close proximity to the data acquisition box. 

Hello Juma,yes the system has been supplied by IMS.

Hi Vukalp, Can you increase the amplitudes on the screen and see if there is any signal looking like P-wave before the signal that you show? Stretch the traces almost exactly in the same way for all sensors so that we can compare them. Plot also the traces aligned with the distance. Please provide images with better quality.

I think the big question is how far away are your sensors from each other. If they are far enough away from each other then you should see a separation of the p-wave / S-wave. Do you have other sensors which could record the event which are further away?

-Also, are all your sensors on the same box?

Это очень похоже на уединенную волну. Данные волны могут "захватываться" разломами. Важно! Необходимо посмотреть материалы на разных сейсмических станциях.