# Seismic trace

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In [seismology](/source/seismology), a '''seismic trace''' is the recorded curve from a single [seismograph](/source/seismometer) when measuring ground movement. The name comes from the curve plotted by a seismograph as the paper roll rotated and the needle left a '''trace''' from which information about the subsurface could be extracted. Today's instruments record the data digitally and the word trace has come to mean the digital curve.

==Complex seismic trace==
The recorded seismic trace is considered the [real](/source/real_number) part of the [complex](/source/complex_number) trace. By phase shifting the recorded trace by 90 degrees, we can obtain the [imaginary](/source/imaginary_number) part of the complex trace. The complex seismic trace is a [complex function](/source/complex_function) whose real and imaginary part are the previously mentioned.<ref name="Barnes">{{cite journal|last=Barnes|first=A.E.|year=2007|title=A tutorial on complex seismic trace analysis|journal=Geophysics|volume=72|issue=6 |pages=W33–W43|bibcode = 2007Geop...72W..33B |doi = 10.1190/1.2785048 }}</ref> From the complex trace, one can now define [seismic attribute](/source/seismic_attribute)s such as the complex amplitude, phase, instantaneous phase and instantaneous frequency.

==References==
{{Reflist}}

Category:Seismology measurement
Category:Seismology

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Adapted from the Wikipedia article [Seismic trace](https://en.wikipedia.org/wiki/Seismic_trace) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Seismic_trace?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.