Reply to Gang Rao’s comments to Preprint egusphere-2023-1671 

Dear reviewer 

Thank you for the constructive comments provided with your review. I fell your comments very pertinent and will certainly make the narrative in this paper much more robust. I went a step forward from your assessment and thoroughly revised the text in terms of its flow and grammar. I have simplified some concepts and added information I thought pertinent to the paper – once more following the comments provided below. 

Your comments, and further changes made to the paper, are addressed below: 

1) Lines 425-427: For clarity, it would be better to mention the M-L scaling relations when making the statement that the recognition of a >200 km long Fault 3 suggests the potential to generate Mw 8.0 earthquakes in this structure alone. 

Reply: The revised paper now stresses the M-L scaling relationships referred to by the reviewer and cites the published articles where these relationships are made clear. As indicated in the work of Trippetta et al. (2019), faults with a length of 150+ km are able to cause, at least, Mw 8.0 earthquakes. I added more detail on this relationship in the text and ‘toned down’ the abstract and main text to refer to a maximum Mw value of 8.0, potentially generated by the faults studied in this paper, and not one that exceeds Mw 8.0. 

2) Arrangement of Figure 1: the color bars are too large on the right side, which can be placed within the main figure. What’s the meaning of “share v. 3.3”? who or which organization shared the data. I suppose the black arrow, at the upper right corner, pointed to the north. On the left, the orientation statistical data about what? fault and/or folds? 

Reply: The rose diagrams showing the trends of main offshore faults were deleted from Figure 1. Also deleted was the reference to ‘share v. 3.3’, which was posted together with the legend. The sources of these data are indicated in the figure caption. Thank you for spotting this incoherence in the figure. 

3) Figure 6, it is unnecessary to repeat the figure caption above the figure “Structural map of SW Iberia superimposed on Total Magnetic Intensity data”. 

Reply: Agreed. The title on top of Figure 6 was deleted. Also changed was the map itself, which now shows Differential Reduction to the Pole (DRTP) data. This change was based on an offline comment by M. Neres from IPMA, Portugal, who recently characterised the shape and distribution of magmatic bodies in SW Iberia. The DRTP data is much akin to the distribution of magnetic anomalies published in Neres et al. (2023b). Tectonics, doi: 10.1029/2022TC007637. Further details on Neres et al. (2023b) work and its main findings are now included in the Introduction and Discussion sections of the revised article. 

4) Figure 8, the authors display the amounts of uplift and horizontal advection measured along each fault. But, the orientation of the bars is inconsistent. Most of them are in a W-S direction. But, some of them are perpendicular to the fault traces. 

Reply: This was done purposefully as: a) the bars will be almost parallel to the fault lines (as shown on the map), near their fault tips, in all faults with a NE-SW strike. This will make the amounts of uplift and horizontal advection confusing to the readers, as they will not be able to separate fault from the quantitative bars; b) the bars oriented at 30o on the map actually highlight the structures with a strike approaching N45, i.e. formed obliquely to the trend of the continental margin. Most of these faults are thrusts and steep reverse faults that seem to differ in length and style from the remaining faults to the east, nearer to the continental slope and shelf. 

5) The direction of Cenozoic tectonic compression: Lines 433, Cenozoic, in a N-S and NW-SE direction; Line 448, Late Cenozoic, dominated by NW-SE tectonic compression; Is there a temporal change in stress field? Is there any geodetic observation regarding the modern stress? In Figure 10c and d, under the NW-SE direction, localized FTBs formed. In the map view, the NW-SE-trending Fault 16 is also a thrust fault? not a tear fault? 

Reply: Yes. There are multiple observations that corroborate a NW-SE direction of tectonic compression, at present. Perhaps the most detailed information on present-day stresses required has been published in Ribeiro et al. (1990), Ribeiro et al. (1996) and more recently in Somoza et al. (2021). Detail derived from these papers were added to the Results and Discussion sections of the paper. Unfortunately, there is no published information on palaeo-stress directions by the simple fact that Miocene-Recent tectonics overprints, structurally speaking, the directions of compression associated with the Pyrenean and older tectonic phases.

Other changes completed:

A) Figures were improved and the text on key seismic sections made larger. All figures were made tidier and clearer to the readers. 

B) The introduction was revised, and information was added to improve its flow. Parts of some paragraphs were also merged or reviewed in relation to the narrative written before and after their appearance. In other words, there was a thorough effort to review the text for typos and small inconsistencies in this first revision round. 

Sincerely yours,

Tiago M. Alves