Shallow Velocity Estimation by Multiples for Monochannel Boomer Surveys

Round 1

Reviewer 1 Report

A very well-written and demonstrated manuscript. The work describes a method to estimate sea-floor velocity using appropriate equations and applies them using appropriate synthetic and real data sets. I recommend publication of this manuscript in Applied Sciences.

Author Response

We thank you for your positive response. Further improvements were implemented in the revised manuscript.

Reviewer 2 Report

The article provides a serious theoretical overview of calculations and theory as such. The chosen methodology is fine. The attached images also add great value. I have no comments on this research.

Author Response

We thank you for your positive response. Further improvements were implemented in the revised manuscript.

Reviewer 3 Report

Review of the manuscript Shallow velocity estimation by multiples for mono-channel Boomer surveys by Vasnaver and Baradello

Reviewer info.

I am a physicist strongly involved in seismic traveltime inversion and uncertainty estimation. I also have some experience with seismic multiple elimination methods. I have never worked with boomer data (small scales), but the concept is the same, so I feel qualified to review this paper.

General opinion

This manuscript is a short presentation of a really simple idea of using peg leg multiples from a single-channel marine survey to estimate the P velocity and thickness of shallow layers. The concept is clearly described and illustrated with both synthetics and field data examples. I am not a native speaker, but for me the language is clear and easy to follow. The motivation of the work is clearly explained. I really like the detailed uncertainty analysis and detailed field data processing, including feathering and phase changes.

Main concerns

1. It seams this article is based on the submitted EAGE abstract, and because of that, it is short, and discussion paragraph is almost missing. I don't understand why authors discuss short offset observations and tangent function approximations for small angles when they also show the best results are for larger offsets (10m). This might be expanded with comparison to more typical methods like refraction tomography and reflection tomography.
2. Recognizing peg leg multiples is very difficult, as their Energy is very small compared to primary reflections. Authors show one case with the successful application of this method, but I am curious if this would be possible without a priori knowledge about the area from previous experiments and boreholes. Is it really doable in case of dipping sea bed (which is typical at shallow waters) or in more complex structures? Usually, I would rely on wide-angle refractions and simple first break tomography to recognize velocities.

Small suggestions

1. Most of presented figures could be merged. Figure 4, 5, 6 and 7 could be merged into one. Similarly Figure 9 and 10, and Figure 11 and 12. I don't see the reason to make them separate figures.
2. the dependence of uncertainty from the offset discussed in line 196 was analytically described in one of papers (Majdański, 2013, Geophysics, doi:10.1190/geo2012-0280.1). It might be interesting for the authors, as it shows that the uncertainty is decreasing with offset for estimated velocity, and decreasing with offset for estimated thickness. Seismic tomography: G. Nolet, 2008, A Breviary of seismic tomography, 10.1017/CBO9780511984709 Reflection tomography: Sherwood et al., 1986, Sherwood, J. W. C., Chen, K. C., and Wood, M., 1986, Depths and interval velocities from seismic reflection data for low-relief structures: Proc. Offshore Tech. Conf., 103–110. Kosloff et al., 1996, Kosloff, D., Sherwood, J. W. C., Koren, Z., Machet, E., and Falkovitz, Y., 1996, Velocity and interface depth determination by tomography of depth migrated gathers: Geophysics, 61, 1511–1523 

Recommendation

I am sure this article should be published. It is well writted, clear and convincing. I suggest merging figures and expanding the discussion slightly. Such minor revisions should be easy to implement.

Author Response

We thank you for your careful revision and your suggestions, which we all took into account. A detailed set of answers to all your points is reported in the attached file.

Author Response File: Author Response.pdf