Dear Mauro and colleagues,

this is an interesting article based on an astonishing effort of field work. Congratulations. It is beyond doubt that a thorough re-appraisal of volcanic deposits is required for enhanced risk analysis.

I have attached an annotated pdf with many comments and change suggestions. I have three main points:

1. Overall, I would like to see some restructuring of the manuscript as many figures in the Appendix would help the reader to better follow your reasoning. Please add several of them in the main body of the manuscript and not only the many maps with outcrop locations.

2. please add definitions to terms you are using that may be used in a subjective way (e.g. syn- and post-eruptive lahars) or numbers with units to statements that you are using in a poorly qualitative way (fine, finer...)

3. being a non-native English speaker myself, I still feel that the manuscript could benefit from a language check.

Best regards.

The paper represents an interesting contribution; new stratigraphic data are presented here for the Pollena and the 1631 plinian eruptions and associated lahars, based on which a new impact area is defined, with important implications on hazard assessment.

I think that authors should better describe their initial assumption and improve the description and interpretation, which are now quite poorly justified or vague. Below are some major points. It is an interesting paper, but it needs to be improved before its publication. Some figures need to be improved. The annotated PDF includes several suggestions.

Terminology. I consider that authors should better define the terminology here used, especially for syn- post and inter-eruptive lahar. Post and inter-eruptive lahars do not necessarily point to similar events. Post-lahars can occur a few months or years after the eruption when the landscape is still responding to the hydrological and sedimentary-yield consequences of the eruption, and lahars are still remobilizing the primary pyroclastic deposits only. Inter-eruptive lahars occur without a direct volcanic influence. I have suggested some references to this point. I understand that authors refer to syn-eruptive lahar as those that originated from the primary pyroclastic deposits only, but the timing can be important for hazard assessment purposes.

Lahar deposit textures are poorly described, please add a figure illustrating the main facies here described (line 377). En-masse deposition here described for lahars is poorly justified and contrasts with several recent studies. Water escape features are not evidence of en-masse deposition. A few descriptions and pictures are included in the appendix; I consider more useful for the reader to add some figures in the main text, is quite annoying to go to the appendix to understand the main text. I suggest including a simple table with a picture of each facies here described and a resume of their main characteristics.

Authors should better describe the componentry of both Pollena and 1631 eruptions, their differences, and how they were used to discriminate syn-eruptive lahars from each one of these eruptions or if stratigraphic relationships were the main criteria. Right now is written as the reader perfectly knows the stratigraphy of the Somma-Vesuvius area.

I suggest authors avoid mixing descriptions with interpretations.

Figure 7 is not a distribution map; is a map that shows the outcrops where lahars from Pollena eruption are outcropping. This map does not allow the reader to understand the source area of lahars nor how the volume of these lahar deposits was estimated. I suggest at least including as a layer the drainage system. And what does the 0 value mean in the thickness scale? In the map, there are several points (white dots) with this value. The same observations for the figure of the lahars associated with the 1631 eruption.

It is not completely clear to me as syn-eruptive and “post(inter)” eruptive lahars from Pollena eruption are discriminated. One of the main parameters is that post-eruptive events crop on top of the humified surface or soil layers with evidence of anthropic use, while syn-eruptive lahar deposits lay directly on top of the primary deposits (line 405). Can authors better explain this point as, for example, for the Avella area, were both syn-eruptive and post-eruptive lahars of the Pollena eruptions are described? Also, it is not clear how the outcrops in the SW area (white dots in figure 6) are interpreted as syn-eruptive if primary deposits from Pollena are not mapped here (based on Figure 5).

Line 422. Why post-eruptive (here consider as inter-eruptive) lahar are still associated with the Pollena eruption and defined as post only because they contain or are overlaid by fragments from Mercato and Avellino eruptions? Just as an example, at Colima volcano, all syn- eruptive, post or inter-eruptive lahars from recent activity contain pumice fragments from the 1913 plinian eruption. Syn-eruptive lahars can erode the substratum during their emplacement. Finally, why are post(inter)-eruptive lahars associated with a specific eruption? Still unclear how is the timing between a syn-eruptive and a post(inter)-eruptive lahar here considered if the post-eruptive events are still correlated to an eruption. Authors can solve this problem by changing the terminology here used and distinguishing between post and inter-eruptive. 

Some lahars from the Valle de Avella and Somma-Vesuvius area show up to 50% of the mud fractions, it could be interesting to define the % of silt and clay, as inter-eruptive lahars could also be discriminated based on their granulometry.

Authors should better explain how the lahar volume is here estimated as the map distribution only shows their outcrops. And if the distribution of fall and PDC deposits from Pollena and 1631 eruptions are here redefined, it could be interesting if authors can estimate the new volume. 

The Manuscript contains a lot of information about occurrence of volcaniclastic flows/lahars in the Vesuvian area (Italy). The work is potentially of interest for an international audience, but, at present, it is too confused and in some part not consistent with current models and physics to be recommended for publication as it is.

The paper is very long and in some part very hard to read due to the long description of data that may be better organised in Tables. I refer in particular to the stratigraphic description and sedimentological analysis, which are not well organised. In particular, I found not appropriate for a paper dealing with stratigraphic analysis not to present photos of the most significant outcrops in the main text. Also, the lithofaces analysis is poorly significant as it is. This is because the lithofacoes codes are introduced without any explanation and they are not summarised in a table (shortening the description).

The grain size data of figure 11 are poorly descriptive if the finest part is not analysed. Also, some of the statistical parameters of Table 1 are not significant, being the distributions very far from gaussian-like.

A lot of inconsistencies are present throughout the manuscript (i.e. Somma-Vesuvius vs. Vesuvius, volcaniclastic flows vs lahars). They need to be accurately checked and corrected.

The calculation of the velocity and dynamic pressure is basically wrong, in absence of a detailed determination of the flow behaviour. The Authors assume the clasts are transported within the flow, but it may be not the case depending on flow conditions. Lahars can transport boulders as large as meters as passive load, solely due to the pore pressure within the underlying flow. On the other hand, it is not possible to derive the velocity of the flow from the deposit as it is presented, because simply it was zero at time of deposition. So, it is not possible to associate a dynamic parameter with a deposit location as in Figure 17.