Physical and mechanical rock properties of a heterogeneous volcano: the case of Mount Unzen, Japan

Kendrick, Jackie E.; Schaefer, Lauren N.; Schauroth, Jenny; Bell, Andrew F.; Lamb, Oliver D.; Lamur, Anthony; Miwa, Takahiro; Coats, Rebecca; Lavallée, Yan; Kennedy, Ben M.

doi:https://doi.org/10.5194/se-12-633-2021

Articles | Volume 12, issue 3

Solid Earth, 12, 633–664, 2021

https://doi.org/10.5194/se-12-633-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Solid Earth, 12, 633–664, 2021

https://doi.org/10.5194/se-12-633-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 12, issue 3

Research article 16 Mar 2021

Research article | 16 Mar 2021

Physical and mechanical rock properties of a heterogeneous volcano: the case of Mount Unzen, Japan

Jackie E. Kendrick et al.

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Final revised paper (published on 16 Mar 2021)
Supplement to the final revised paper
Preprint (discussion started on 09 Oct 2020)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of "Physical and mechanical rock properties of a heterogeneous volcano; the case of Mount Unzen, Japan"', Michael Heap, 27 Oct 2020
- AC1: 'Reply to reviewer 1, Michael Heap', Jackie E. Kendrick, 17 Dec 2020
RC2: 'Physical and mechanical rock properties of a heterogeneous volcano; the case of Mount Unzen, Japan: A review', Philip Benson, 05 Nov 2020
- AC2: 'Reply to reviewer 2, Phil Benson', Jackie E. Kendrick, 17 Dec 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Jackie E. Kendrick on behalf of the Authors (14 Jan 2021) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Jan 2021) by Federico Rossetti

RR by Michael Heap (27 Jan 2021)

Suggestions for revision or reasons for rejection

I have now read through the authors’ replies to my comments, their replies to comments of the second reviewer, and the revised manuscript. It is clear that the authors have seriously considered the various comments, particularly the comment concerning the precision/accuracy of the TinyPerm field permeameter. As a result, the manuscript now also serves as a reference for those interested in assessing the use of field permeameters in the geosciences, which adds an extra dimension to this data-rich manuscript. I have some very, very minor final comments (technical corrections), outlined below. After these have been addressed, or dismissed, I think the manuscript can be accepted for publication.

Mike Heap (University of Strasbourg)

Line 735 (and in the discussion): Since the manuscript now assesses the accuracy/precision of the TinyPerm unit, it may be worth describing/discussing the measurements provided in the Appendix of Farquharson et al. (2015, already cited). These authors measured the permeability of several large blocks of rock using the TinyPerm and compared the values with laboratory measurements of permeability (for cylindrical samples cored from the measured blocks). Heap et al. (2017), however, found that differences between the TinyPerm measurement on a block of rock and the permeability of a cylindrical sample cored from the block and measured in the laboratory can vary by up to three orders of magnitude. These authors suggested that uneven rock surfaces and the presence of altered/weathered outer layer could be to blame for the observed discrepancy. I’m not suggesting that these latter points influenced the permeability estimates provided in the submitted manuscript, but it may be worth flagging this somewhere to warn readers of these potential problems.

Heap, M. J., Kennedy, B. M., Farquharson, J. I., Ashworth, J., Mayer, K., Letham-Brake, M., ... & Dingwell, D. B. (2017). A multidisciplinary approach to quantify the permeability of the Whakaari/White Island volcanic hydrothermal system (Taupo Volcanic Zone, New Zealand). Journal of Volcanology and Geothermal Research, 332, 88-108.

Line 1078: “modulus”.

Line 1320: “modulus”.

Line 1323: “modulus”.

Line 1325: The empirical relationships presented in Heap et al. (2020) describe a combined dataset (basalts, andesites, dacites, etc. from volcanoes all over the world). The relationship presented in the submitted manuscript is for dacites from Mt Unzen. Although Heap et al. (2020) play down the role of rock type on Young’s modulus, perhaps this is another reason why the relationships differ?

Line 1355: “modulus”.

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ED: Publish subject to technical corrections (27 Jan 2021) by Federico Rossetti

ED: Publish subject to technical corrections (27 Jan 2021) by Federico Rossetti(Executive Editor)

Short summary

The last lava dome eruption of Mount Unzen (Japan) ended in 1995, but ongoing instability means much of the area remains an exclusion zone. The rocks in the lava dome impact its stability; heterogeneity (contrasting properties) and anisotropy (orientation-specific properties) can channel fluids and localise deformation, enhancing the risk of lava dome collapse. We recommend using measured material properties to interpret geophysical signals and to model volcanic systems.