Dear Editor,
Thank you very much for the helpful comments and the opportunity to revise our
paper. The comments are shown here in black print, and our responses are shown in red.
Sincerely,
Michael Wysession
Comments:
Assoc. Editor:
The authors analyze seismic signals from a variety of sources encountered in an urban
battlefield, in this case Baghdad in 2006. Mortar rounds, IEDs, munition explosions, and
aircraft are among the signals presented. Acoustic arrivals from these events tend to
dominate the recorded data, though seismic arrivals appear as well. A combination of
acoustic and seismic techniques are employed in an attempt to characterize the various
sources. There is much here that will interest the BSSA audience, but the presentation
requires significant revision before this paper can be accepted. The reviewer recommends
numerous changes below; I add some additional comments here and in an attached copy
of the manuscript. The authors should consider all of these as they revise the paper.
1) Some of the methods are discussed very briefly, which leaves questions about the
results. An example is the estimation of source moments and yields from the P spectra.
The text does not mention that the equations apply to fully-contained, underground shots
- coupling is critical here, but mostly ignored. A footnote under Table 1 does give an
assumed coupling factor, but this issue deserves to be addressed in the text. Likewise, the
discussion of the airwave modeling is limited to one paragraph; few details are presented.
Overall, presenting fewer methods but discussing them more fully would be better.
Fixed. These descriptive sections have been considerably lengthened, with much more
detail given.
2) I found the frequent mention of both local and UTC times to be confusing and
unnecessary. It would be better to use just the UTC times throughout the text and figure
captions, since these are the times shown in all the plots. The corresponding local time
could be mentioned once in the text, say in the discussion of Figure 1.
Done. We now consistently use UTC times, and introduce the conversion from local time
at the beginning.
3) Several of the figures and captions seem to have been hastily prepared. Some captions
refer to times outside the plotted range; the caption for Fig 2 mentions an effect of
distance, but distances for the signals aren't given; Fig 12 has the same plot as Fig 11;
subplots b and c are missing in Fig 13; the plots switch arbitrarily between velocity and
displacement - consistent units and scales would help readers compare some of the plots;
the reviewer also comments on figure preparation.
Done. Significant revisions have been done to the figures, especially in the area of
labeling.
4) The reference list needs some attention: a few cited papers are not in the list, and some
listed ones are not cited in the text.
Done. The reference list has been carefully revised, and a Data and Resources section has
been added.
Reviewer #1: Dear authors,
It was my pleasure to read your paper. I would like to give you my feedback as follows.
Hopefully it is helpful for your paper.
A. manuscript
1. [line 45] "Of note are the similarity and repetitiveness of the waveforms" : How much
are these similar to each other? I cannot find any quantitative estimates such as
correlation coefficients in the manuscript.
Done. We added figure 7 and calculated cross-correlation coefficients.
2. [line 47] Typo. Figure 1c --> Figure 1d.
Done
3. [line 49] "Figure 2 shows waveforms from two VBIEDs." Are these airwave
waveforms?
Waveforms include the whole explosion signals, not only airwaves. TO help clarify
this, we marked the P arrival in Figure 3.
4. [line59-61] I can not find the source location of the two events in the manuscript. I
wonder if you could include a location map of these events.
We didn’t locate those events – we only had one seismic station. We clarified this by
including reported descriptive locations.
5. [line 84] Typo. (19:40 GMT, Figure 5b)) --> (19:40 GMT, Figure 5b)
Done.
6. [line 117] Sometimes just local time without UTC is mentioned or the other way,
which may cause some confusions to readers. I wonder if you could use local time and
UTC at the same time in the manuscript.
Done. We consistently switched to UTC time, and added that local time in Baghdad is
3 hours ahead of UTC. And we now cite local time only when we felt it was relevant
to the discussion.
7. [line 212-214] References are needed.
Fixed. Text was altered so that a reference is no longer needed.
8. [line 217-220] References are needed.
Done. Reference added.
9. [line 237-238] "relatively" : What do you mean by using "relatively"? Do you have a
reference value?
Done. The second clause now states: “in comparison to the values for the interval…”
10. [line 256-257] The description here is not clearly figured out in Figure 11. Much
better resolution is needed for Figure 11. Also Figure 11 are same to Figure 12. I think it
is a mistake. You need to change Figure 12 as a correct one.
Done.
11. [line 273-275] Here you used the unit "mph"; mile per hour. In other place, you used
SI unit such as km/s. I think that the unit in the manuscript should be SI. Also, I can not
recalculate the number 110 mph and 140 mph. There is no description on the velocity of
sound. It will be good if you can show one example of calculation with the velocity of
sound you used.
Done. Changed to SI units, added the speed of sound in kph, and added symbols to
identify frequencies used in the vehicle speed calculations.
12. [line 289-302] The description on the inversion process is too simple. Much detailed
explanation on the inversion process such as description on the initial model, iteration
process, global minimum and so on is needed. Also the synthetic waveform calculation
needs more descriptions with authors' specific case even though this is a popular
technique.
Done. These sections were lengthened with more details added.
13. [line 310] I can not find the information of Keith et al., 2002 in the reference list of
the manuscript.
Done. The reference [Koper et al., 2002] was erroneously listed as [Keith et al., 2002]
14. [line 319] Grammer. "to minimizing" --> " to minimize"
Done.
15. [line 319-321] The observed waveforms used for the grid search are not included in
the manuscript.
Done. Figure added (Figure 20).
16. [line 327-328] I am skeptic about the calculation of yield with a simple table relating
moment with yield. As you mentioned in the later part of the manuscript, the line 359
through 376, I think the yield estimate is much more complicated. I suggest using a
relationship of relative energy difference rather than using yield estimates. Also, I can not
find the information of Lahr(2000) in the reference list of the manuscript.
Fixed. The yield estimates were recalculated, with new values higher than the old
because of the use of different values of P velocity and density, resampling observed
spectra at 0.01 Hz, and removing a factor of 2 that was mistakenly propagated
through calculations. The Lahr (2000) reference information was added to the
section on Data and Resources.
17. [line 331-342] More interpretation and explanation on the scaling factor calculation
result and figure 18 are needed. The "show" in the line 337 should be "shown".
Fixed. This figure was removed from the paper, as well as the calculations in the
text. The authors felt that we need to obtain additional ground truth data before we
can address this issue.
B. Table
18. [line 509-510] How did you choose the ratio 1000/15? I can not find the information
of Lahr(1988) in the reference list of the manuscript.
Fixed. Information was added about Lahr (2000), with the source of information for
this calculation added to the Data and Resources section.
C. Figures
19. [Figure 1 (d)] In this spectrum, the noise spectrum is not included. I wonder if you
could add noise spectrum for figuring out the bandwidth of signals. Also it wil be much
clearer for readers to understand your work if you could include the detailed steps for
calculating this smoothed spectrum, which is currently not described in the manuscript. I
would like to ask same requirements for other spectra in different figures.
Fixed. We have added a discussion about the noise issue and added a figure about
the noise spectrum (Figure 9). No smoothing is involved in the way the spectra
presented. This has been clarified.
20. [Figure 4] A high quality map using a graphic program such as GMT is needed rather
than using a Google map.
Done. This is in the new Figure 5.
21. [Figure 5] there is no (a), (b) and (c) in the figure 5.
Fixed.
22. [Figure 7] A MFT result with a high resolution is needed.
Fixed – added.
23. [Figure 8] How's the unit of the numbers in the figure 8? A typo in the Caption line
559 should be corrected: "Numbers on the right" --> "Numbers on the left"
Fixed.
24. [Figure 9] The time frame of the figure does not match with the description of the
caption. In the caption line 569, authors mentions "just after 19:15". But the time frame
of the figure does not include the time series on 19:15.
Fixed.
25. [Figure 11-Figure 14] Much better resolution is reguired for these figures to figure
out doppler effect described in the manuscript.
Done. Higher resolution figures are now shown.
26. [Figure 16] Typo. (f) --> (e)
Fixed.
27. [Figure 19] Figure 19(b) shows a 2.5 second window while the lowest frequency of
the specta in Figure 19(c) is 10 seconds. So, the time domain frame does not match with
the frequency band.
Fixed. All figures now have amplitude spectra frequency bounds that match the window
lengths.