the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 11 May 2022
Upper lithospheric structure of northeastern Venezuela from joint inversion of surface wave dispersion and receiver functions
Antonio Villaseñor
Elizabeth Berg
Andrés Olivar-Castaño
Mariano Arnaiz-Rodríguez
Sergi Ventosa
Ana M. G. Ferreira
Abstract. We use 1.5 years of continuous recordings from an amphibious seismic network deployment in the region of northeast South America and southeast Caribbean to study the crustal and uppermost mantle structure through a joint inversion of surface wave dispersion curves determined from ambient seismic noise and receiver functions. The availability of both ocean bottom seismometers (OBSs) and land stations makes this experiment ideal to determine the best processing methods to extract reliable empirical Green’s functions (EGFs) and construct a 3D shear velocity model. Results show EGFs with high signal-to-noise ratio for land-land, land-OBS and OBS-OBS paths from a variety of stacking methods. Using the EGF estimates, we measure phase and group velocity dispersion curves for Rayleigh and Love waves. We complement these observations with receiver functions, which allow us to perform an H-k analysis to obtain Moho depth estimates across the study area. The measured dispersion curves and receiver functions are used in a Bayesian joint inversion to retrieve a series of 1D shear-wave velocity models, which are then interpolated to build a 3D model of the region. Our results display clear contrasts in the oceanic region across the border of the strike-slip fault system San Sebastian - El Pilar as well as a high velocity region that corresponds well with the continental craton of southeastern Venezuela. We resolve known geological features in our new model, including the Espino Graben and the Guiana Shield provinces, and provide new information about their crustal structures. Furthermore, we image the difference in the crust beneath the Maturin and Guárico Sub-Basin.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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- Final revised paper
Journal article(s) based on this preprint
Roberto Cabieces et al.
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-230', Anonymous Referee #1, 20 Jun 2022
This is a study in which the authors propose a new 3-D model of shear wave velocity (Vs) and moho depth in northern Venezuela using both reciever function on their own for Moho depth and a joint inversion of Rayleigh and Love phase and group velocity measurements obtained from noise cross-correlations, using both land-based and ocean-bottom seismometers. The authors use H-k stacking for measuring Moho depth and a linearised least-squares inversion to obtain surface wave dispersion curves and then use a hierarchical, transdimensional bayesian inversion scheme to jointly invert surface-wave data and reciever function data for shear wave velocity. The results show clear geographical coherence and known tectonic features. Overall, I think this is a good study that improves our knowledge of the area. However, I have some concerns about the methods and some figures need to be improved.
Major Comments
The authors use a joint inversion of reciever functions and surface-wave data, but they use reciever functions alone to measure the Moho depth. I do not understand why they perform a separate measurement for Moho depth instead of obtaining it from the joint inversion. Why use reciever functions in an inversion if not to better constrain the location of interfaces and especially the Moho? Figure 9 shows that the Moho is clearly visible on the inversion results. Consequently, the results of Moho depth measurements and the results of the Vs inversion as shown on Figure 11 do not seem to match, for example on profiles B-B' and D-D'. Also, some of the Moho depth measurements such as shown in Figure 8 for station PRPC are apparently not well constrained, maybe a joint inversion could have helped there.
Minor Comments
Figure 1 is hard to read. The colorful background map and the many earthquakes make finding the stations challenging. As the authors are using seismic noise and teleseismic data, it is not clear why the local seismicity is shown. Figures 2 and 3 refer to Figure 1 for the location of stations CUBA, LAPC and CMPC, but those are not shown on the map. An indication of the location of the study area on the small map in the upper right corner would also be useful.Page 4, line 99: The steps are listed in the wrong order, the authors first show how to retrieve Rayleigh and Love wave dispersion measurements, then how to obtain the RF and Moho depth measurements.
Page 5: It would be useful to indicate the direction of the main noise sources. This would make it easier to understand the kind of asymetries and biases that are to be expected from the noise cross-correlations.
Figure 4: What are the red and blue bars on figures c-f? Why is the period scale logarithmic on figures a and b and linear on figures c-f? The caption needs to be clarified, like line 85: 'd) and f) Love velocity histograms of dispersion measures for Rayleigh and Love waves, respectively.'
Page 6, line 60: 'The measurements of phase and group velocity from all station pairs at different periods', not 'in different periods'
Figure S1: The caption is unclear: is this the output of the picking software?
Page 8, line 44: Did the authors use thinning for the McMC? 100 000 iterations on 40 cores does not seem like a lot for a joint transdimensional hierarchical bayesian inversion, would it be possible to show a density plot to show the inversion has fully converged?
Page 9, line 84: Could the elongated feature seen on surface wave velocity maps be due to smearing? The resolution tests show some smearing in the area in the same direction.
Figures 5 and 6: Would it be possible to show the relevant locations like in figure 10? Figure 1 is a long way and has a different size.
Page 14, line 16: shouldn't it be 'slab roll-back' rather than 'slab-roll back'?
Page 16, line 08: It would be necessary to cite the networks used in this study, the relevant information and DOI can be found on http://www.fdsn.org/networks/
Citation: https://doi.org/10.5194/egusphere-2022-230-RC1 -
AC1: 'Reply on RC1', Roberto Cabieces, 15 Oct 2022
We are grateful to RC1 to provide very constructive and thorough comments on our manuscript. We have responded in detail to each comment in the attached document “RC1_respond” in blue (RC1) text for each point individually and we have included the corrections related to the reviews (in blue) in a separated file “Manuscript corrections”, corrected figures (Figs. 4, 5,6, 10 and 11) and new figures (Figs. S11 and S12 in the Supplementary Material) according to the reviews in the new Supplementary Material file.
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AC1: 'Reply on RC1', Roberto Cabieces, 15 Oct 2022
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RC2: 'Comment on egusphere-2022-230', Franck Audemard, 10 Aug 2022
The authors of this study propose a new 3D model of shear wave velocity (Vs) and moho depth of eastern Venezuela, from the Caribbean Basin in the North to the Guiana Shield in the South, using both reciever function alone for Moho depth imaging and a joint inversion of Rayleigh and Love phase and group velocity measurements obtained from noise cross-correlations, using an amphibious (land-ocean) seismometer array. This 3D model is build from 1D profiles spaced 0.5°x0.5°. The authors use H-k stacking for measuring Moho depth and a linearised least-squares inversion to obtain surface wave dispersion curves and then use a hierarchical, transdimensional bayesian inversion scheme to jointly invert surface-wave data and reciever function data for shear wave velocity. The results show clear geographical coherence and known geologic features. Overall, this study seems to improve knowledge of the area. However,even if my field of expertise is not the use of earthquake waves to image Earth Interior, I have three major concerns about this contribution:
1) Some figures need to be improved. Particularly, Figure 1 (left panel) should only show seismicity used during this evaluation,. Minor comments on the other figures are provided in an annotated pdf.
2) Some previous internationally-reviewed studies on crustal structure of the same region by local researchers (e.g., Schmitz et al, 2005, 2021), using other methods (e.g. wide-angle data) are curiously not cited. Of course, comparison of results between those different studies (with different approaches: active seismics) is not presented.
3) the authors keep the comparison of their results to other similar (geophysical/seismological: passive seismics) studies: Niu et al.; Miller et al.; Masy et al.; Arnaiz et al., and so on. It would seem that they are well aware of the Bolivar Project results. However, even the aim of the paper being the correlation/imaging/identification of geological/tectonic/geodynamic features, little referencing of geological studies is applied. For instance, the Espino Graben geometry and its Cenozoic-Quaternary southward directed inversion is well known from oil-industry seismics and other studies.
Minor comments, typo and form corrections are provided in annotated pdf of the contribution.
We wish to see this original version improved soon and quickly published in final format
- AC2: 'Reply on RC2', Roberto Cabieces, 15 Oct 2022
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-230', Anonymous Referee #1, 20 Jun 2022
This is a study in which the authors propose a new 3-D model of shear wave velocity (Vs) and moho depth in northern Venezuela using both reciever function on their own for Moho depth and a joint inversion of Rayleigh and Love phase and group velocity measurements obtained from noise cross-correlations, using both land-based and ocean-bottom seismometers. The authors use H-k stacking for measuring Moho depth and a linearised least-squares inversion to obtain surface wave dispersion curves and then use a hierarchical, transdimensional bayesian inversion scheme to jointly invert surface-wave data and reciever function data for shear wave velocity. The results show clear geographical coherence and known tectonic features. Overall, I think this is a good study that improves our knowledge of the area. However, I have some concerns about the methods and some figures need to be improved.
Major Comments
The authors use a joint inversion of reciever functions and surface-wave data, but they use reciever functions alone to measure the Moho depth. I do not understand why they perform a separate measurement for Moho depth instead of obtaining it from the joint inversion. Why use reciever functions in an inversion if not to better constrain the location of interfaces and especially the Moho? Figure 9 shows that the Moho is clearly visible on the inversion results. Consequently, the results of Moho depth measurements and the results of the Vs inversion as shown on Figure 11 do not seem to match, for example on profiles B-B' and D-D'. Also, some of the Moho depth measurements such as shown in Figure 8 for station PRPC are apparently not well constrained, maybe a joint inversion could have helped there.
Minor Comments
Figure 1 is hard to read. The colorful background map and the many earthquakes make finding the stations challenging. As the authors are using seismic noise and teleseismic data, it is not clear why the local seismicity is shown. Figures 2 and 3 refer to Figure 1 for the location of stations CUBA, LAPC and CMPC, but those are not shown on the map. An indication of the location of the study area on the small map in the upper right corner would also be useful.Page 4, line 99: The steps are listed in the wrong order, the authors first show how to retrieve Rayleigh and Love wave dispersion measurements, then how to obtain the RF and Moho depth measurements.
Page 5: It would be useful to indicate the direction of the main noise sources. This would make it easier to understand the kind of asymetries and biases that are to be expected from the noise cross-correlations.
Figure 4: What are the red and blue bars on figures c-f? Why is the period scale logarithmic on figures a and b and linear on figures c-f? The caption needs to be clarified, like line 85: 'd) and f) Love velocity histograms of dispersion measures for Rayleigh and Love waves, respectively.'
Page 6, line 60: 'The measurements of phase and group velocity from all station pairs at different periods', not 'in different periods'
Figure S1: The caption is unclear: is this the output of the picking software?
Page 8, line 44: Did the authors use thinning for the McMC? 100 000 iterations on 40 cores does not seem like a lot for a joint transdimensional hierarchical bayesian inversion, would it be possible to show a density plot to show the inversion has fully converged?
Page 9, line 84: Could the elongated feature seen on surface wave velocity maps be due to smearing? The resolution tests show some smearing in the area in the same direction.
Figures 5 and 6: Would it be possible to show the relevant locations like in figure 10? Figure 1 is a long way and has a different size.
Page 14, line 16: shouldn't it be 'slab roll-back' rather than 'slab-roll back'?
Page 16, line 08: It would be necessary to cite the networks used in this study, the relevant information and DOI can be found on http://www.fdsn.org/networks/
Citation: https://doi.org/10.5194/egusphere-2022-230-RC1 -
AC1: 'Reply on RC1', Roberto Cabieces, 15 Oct 2022
We are grateful to RC1 to provide very constructive and thorough comments on our manuscript. We have responded in detail to each comment in the attached document “RC1_respond” in blue (RC1) text for each point individually and we have included the corrections related to the reviews (in blue) in a separated file “Manuscript corrections”, corrected figures (Figs. 4, 5,6, 10 and 11) and new figures (Figs. S11 and S12 in the Supplementary Material) according to the reviews in the new Supplementary Material file.
-
AC1: 'Reply on RC1', Roberto Cabieces, 15 Oct 2022
-
RC2: 'Comment on egusphere-2022-230', Franck Audemard, 10 Aug 2022
The authors of this study propose a new 3D model of shear wave velocity (Vs) and moho depth of eastern Venezuela, from the Caribbean Basin in the North to the Guiana Shield in the South, using both reciever function alone for Moho depth imaging and a joint inversion of Rayleigh and Love phase and group velocity measurements obtained from noise cross-correlations, using an amphibious (land-ocean) seismometer array. This 3D model is build from 1D profiles spaced 0.5°x0.5°. The authors use H-k stacking for measuring Moho depth and a linearised least-squares inversion to obtain surface wave dispersion curves and then use a hierarchical, transdimensional bayesian inversion scheme to jointly invert surface-wave data and reciever function data for shear wave velocity. The results show clear geographical coherence and known geologic features. Overall, this study seems to improve knowledge of the area. However,even if my field of expertise is not the use of earthquake waves to image Earth Interior, I have three major concerns about this contribution:
1) Some figures need to be improved. Particularly, Figure 1 (left panel) should only show seismicity used during this evaluation,. Minor comments on the other figures are provided in an annotated pdf.
2) Some previous internationally-reviewed studies on crustal structure of the same region by local researchers (e.g., Schmitz et al, 2005, 2021), using other methods (e.g. wide-angle data) are curiously not cited. Of course, comparison of results between those different studies (with different approaches: active seismics) is not presented.
3) the authors keep the comparison of their results to other similar (geophysical/seismological: passive seismics) studies: Niu et al.; Miller et al.; Masy et al.; Arnaiz et al., and so on. It would seem that they are well aware of the Bolivar Project results. However, even the aim of the paper being the correlation/imaging/identification of geological/tectonic/geodynamic features, little referencing of geological studies is applied. For instance, the Espino Graben geometry and its Cenozoic-Quaternary southward directed inversion is well known from oil-industry seismics and other studies.
Minor comments, typo and form corrections are provided in annotated pdf of the contribution.
We wish to see this original version improved soon and quickly published in final format
- AC2: 'Reply on RC2', Roberto Cabieces, 15 Oct 2022
Peer review completion
Journal article(s) based on this preprint
Roberto Cabieces et al.
Roberto Cabieces et al.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(3983 KB) - Metadata XML
-
Supplement
(5459 KB) - BibTeX
- EndNote
- Final revised paper