<p>I've seen data like this before. My research focused on acquiring/processing both vertical and horizontal component data in subsurface environments characterized mainly by saturated and/or unconsolidated facies. So, it's entirely possible even for a that kind of surface-wave to display such low apparent velocities.</p>

<p>What I think you are seeing at that particular offset and traveltime is the Rayleigh-wave beginning to '<a href="https://earthscience.stackexchange.com/questions/14414/seismic-dispersion-what-does-it-really-mean-and-what-causes-it">disperse</a>' - AKA seismic dispersion beginning to manifests itself as a results of the wavefield convolving with layering and near-surface heterogeneity. </p>

<p>As for a refraction arrival, if it's indeed present, it should be extremely weak and probably only discernible via some kind of gain (e.g. AGC).</p>

CC BY-SA 4.0
2019-11-05T12:36:48.183Z
would it be possible that you can share your research's paper?
Carlos Javier
CC BY-SA 4.0
2019-11-05T15:14:31.913Z
Absolutely, please visit this web-page and go to my thesis link (https://subsurfacesee.org/). Be advised that particular research and paper concentrated on only SH- and Love-waves.
nate
CC BY-SA 4.0
2019-11-04T03:23:27.897Z
2019-11-04T03:34:26.340Z
2019-11-04T03:34:26.340Z
nate
<p>I ran a 60 m line intended for surficial seismic refraction. Energization with hammer. 12 (10 hz vertical 5 m spaced) geophones and 5 shots (15 m spaced). Record length 0.5 s. Thanks to a borehole near a strata of man-made gravelly silt (0.40 m) and very soft silty clay (to 5 m) and then clay improves its consistency deeper were identified. My seismic traces seemed to be ok, but at office the principal wave train gives 200 m/s and first arrivals refractions are so weak that they cannot be easily identified. I think the principal train wave shadows them.</p>

<p><strong>My question: What is the meaning of a 200 m/s train wave?</strong></p>

<p><a href="https://i.sstatic.net/lQI6K.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/lQI6K.png" alt="enter image description here"></a></p>

CC BY-SA 4.0
2019-08-04T23:38:49.340Z
That's pretty slow... slower than air velocity (300m/s). Are you sure about your measurement?
Antonio
CC BY-SA 4.0
2019-08-09T19:04:21.233Z
Question edited to clarify point.
Carlos Javier
<geophysics><seismology><seismic>
Wave train 200 m/s meaning
Carlos Javier
# Wave train 200 m/s meaning

(Asked by: username_0 on 2019-07-23)

I ran a 60 m line intended for surficial seismic refraction. Energization with hammer. 12 (10 hz vertical 5 m spaced) geophones and 5 shots (15 m spaced). Record length 0.5 s. Thanks to a borehole near a strata of man-made gravelly silt (0.40 m) and very soft silty clay (to 5 m) and then clay improves its consistency deeper were identified. My seismic traces seemed to be ok, but at office the principal wave train gives 200 m/s and first arrivals refractions are so weak that they cannot be easily identified. I think the principal train wave shadows them.

**My question: What is the meaning of a 200 m/s train wave?**

[![enter image description here](https://i.sstatic.net/lQI6K.png)](https://i.sstatic.net/lQI6K.png)

**Tags:** geophysics, seismology, seismic

> **Comments:**
> **username_1**: That's pretty slow... slower than air velocity (300m/s). Are you sure about your measurement?  
> **username_0**: Question edited to clarify point.  

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## 1 answers

### Answer by username_2 on 2019-11-04. Score: 1 | Accepted answer

I've seen data like this before. My research focused on acquiring/processing both vertical and horizontal component data in subsurface environments characterized mainly by saturated and/or unconsolidated facies. So, it's entirely possible even for a that kind of surface-wave to display such low apparent velocities.

What I think you are seeing at that particular offset and traveltime is the Rayleigh-wave beginning to '[disperse](https://earthscience.stackexchange.com/questions/14414/seismic-dispersion-what-does-it-really-mean-and-what-causes-it)' - AKA seismic dispersion beginning to manifests itself as a results of the wavefield convolving with layering and near-surface heterogeneity.

As for a refraction arrival, if it's indeed present, it should be extremely weak and probably only discernible via some kind of gain (e.g. AGC).

> **Comments:**
> **username_0**: would it be possible that you can share your research's paper?  
> **username_2**: Absolutely, please visit this web-page and go to my thesis link (https://subsurfacesee.org/). Be advised that particular research and paper concentrated on only SH- and Love-waves.  

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