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The two images below correspond to two processed seismic cross-sections. My question is this: why at/near 0 Hz is there "lots" of seismic energy still present? Most if not all of the lower end of the bandwidth stops at 10 - 15 Hz.

enter image description here

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  • $\begingroup$ Is this land or marine data? $\endgroup$ – stevej Apr 5 '18 at 20:59
  • $\begingroup$ It is near-surface (9 - 50 m) land data. $\endgroup$ – Nathan Benton Apr 6 '18 at 16:23
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Typically seismic data should oscillate around 0 amplitude in the time domain, i.e. there should be just as much positive amplitude as there is negative (otherwise the ground would have had a net displacement in some direction). This is the energy at 0 Hz in the amp spectrum. It is like a bulk shift (DC shift) on the data.

So... unless the ground was permanently displaced by your seismic source, this is probably just an artifact. It could be as simple as: you used too few data to calculate your amplitude spectrum (e.g. small window, etc). Or it could be a super low frequency artifact coming from data processing.

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