The Mobility of Landslides in Pumice: Insights from a Flume Experiment

Round 1

Reviewer 1 Report

As Iverson (2015) pointed out as below, it is necessary to interpret the experimental results with attention to scaling in small-scale flume experiments.

"relative to full-scale natural events, miniaturized landslides and debris flows exhibit disproportionately large effects of viscous shear resistance and cohesion as well as disproportionately small effects of excess pore-fluid pressure that is generated by debris dilation or contraction. This behavioral divergence grows in proportion to H³, where H is the thickness of a moving mass.” 

I don't think it is appropriate to estimate the effect of granular crushing from small-scale experimental results in which granular crushing does not occur, as described on lines 368-370. Therefore, I think it is necessary to revise the text according to Iverson (2015) for the comparison with the full-scale phenomenon from lines 356 to 359.

However, if we limit to discuss about the area of weathered pyroclastic materials, it can be assumed that grain crushing is likely to occur during a real-scale landslide initiation, so we can infer that the water content has a large effect on landslide mobility.

Iverson, R.M., Scaling and design of landslide and debris-flow experiments, Geomorphology (2015), http://dx.doi.org/10.1016/j.geomorph.2015.02.033

Author Response

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Reviewer 2 Report

IT IS INTERESTING STUDY FOR EARTHQUAKES    2018 Eastern Iburi earthquake,  Japan

. I appreciate authors attempt. However, i have some limitations.
1. What is the scope in the study, can we compare with other conditions, can you please elaborate as I am not sure how authors decided scale 1:300  (

 A flume apparatus 16 constructed at a 1:300 scale was used to examine the mobility of landslides with pumice?)
2. Is there any  mathematical  model for this study for evaluation/ validation ?
3. Which control measures you adopted for your study?
4. Have you developed any Risk Model? If yes - how and if now - why
5. Limitations in the study?
6. Length of data used in the study?

I am happy to review the revised version.

typos : it should be Void ratio (e)  Table (1)

Major revision

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Reviewer 3 Report

The manuscript is a good job , clear in its approach, experimentation and conclusions. But it is necessary to make some adjustments in the figures: * Figure 1: some toponyms need to be added for better understanding (Japan, Hokkaido, for example...). The position of A on the general map of Japan and of B on A should also be referenced. * Figures 3.4 and 5: The meaning and units of the parameters represented in the graphs (X and Y axes) must be explained in the caption of the figure

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Reviewer 4 Report

14^th September 2022

Review of the paper ‘The mobility of landslides in pumice insights from a flume experiment’ by Noviandi et al. for the Water journal

This is an interesting paper, presenting a nice study about the underground stability problems.

I have no major comments on the paper, as it is interesting, nicely written and deals with an interesting topic on landslides in very high-porosity pumice deposits, with a application of a physical experiment. It is suitable for the selected journal and English language is OK (no grammar/typos are present).

There are some points which should be considered, to improve the paper:

  Line 129: Add a geological map and some more detailed geological description, not only 'sedimentary rocks covered by...'.

 138-151: When was the analysis date? Did the geotechnical properties of pumice change from the sampling dates to the analysis dates?

 146: Were there any changes between the samples from 2018 to 2019 sampling dates?

153 (Figure 1): Add some photos of the locations and indicate where were the samples taken.

197 (Figure 2): Length of the upper part of the segment A is missing.

200: What was the reason to collect the samples only from the location 2?

255 (Figure 3): I think it is a bit misleading to plot the last point on the graph, because the L/H is indeed much greater. The distance of the outlet was obviously too short for the maximum saturation. I suggest to extrapolate the line right of the S=0.6 value, with the same slope up to to S=1. Leave the last point where it is (it is a measured one), but I suggest using a different symbol for the additional extrapolated line.

270 (Chapter 4.1): Would it be possible to test and measure the connectivity of the pores in the pumice? Do you have any data of the ratio of the dead pores to the total volume of pores?

323 and later: The pumice is not ‘yours’, please change ‘our’ to ‘tested’ or something similar.

356-358: A higher water content during the actual landslide is quite an expected fact.

365-368: Apart from allowing water to escape from internal voids, crushing can also increase water pressure and additionally mobilize the landslide (causing also a higher L/H ratio). Please add a comment on this.

Author Response

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Round 2

Reviewer 2 Report

Revision is appropriate