Assessment of the peak tsunami amplitude associated with a large earthquake occurring along the southernmost Ryukyu subduction zone in the region of Taiwan

Sun, Yu-Sheng; Chen, Po-Fei; Chen, Chien-Chih; Lee, Ya-Ting; Ma, Kuo-Fong; Wu, Tso-Ren

doi:https://doi.org/10.5194/nhess-18-2081-2018

Articles | Volume 18, issue 8

https://doi.org/10.5194/nhess-18-2081-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/nhess-18-2081-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 8

Research article

|

01 Aug 2018

Research article |

| 01 Aug 2018

Assessment of the peak tsunami amplitude associated with a large earthquake occurring along the southernmost Ryukyu subduction zone in the region of Taiwan

Yu-Sheng Sun, Po-Fei Chen, Chien-Chih Chen, Ya-Ting Lee, Kuo-Fong Ma, and Tso-Ren Wu

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Final revised paper (published on 01 Aug 2018)
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Preprint (discussion started on 06 Nov 2017)
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Status: closed

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

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RC1: 'Review from the tsunami modeling point of view', Anonymous Referee #1, 24 Nov 2017
- AC1: 'Reply to Anonymous Referee #1', Yu-Sheng Sun, 12 Feb 2018
- AC3: 'Figures and Captions correction', Yu-Sheng Sun, 12 Feb 2018
- AC4: 'Reply to Anonymous Referee #1, PDF', Yu-Sheng Sun, 12 Feb 2018
RC2: 'Review of "Assessment of peak tsunami amplitude associated with..."', Anonymous Referee #2, 10 Dec 2017
- AC2: 'Reply to Anonymous Referee #2', Yu-Sheng Sun, 12 Feb 2018
- AC5: 'Reply to Anonymous Referee #2, PDF', Yu-Sheng Sun, 12 Feb 2018

Peer-review completion

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

ED: Reconsider after major revisions (further review by editor and referees) (04 Mar 2018) by Piero Lionello

AR by Yu-Sheng Sun on behalf of the Authors (27 Mar 2018) Author's response Manuscript

ED: Reconsider after major revisions (further review by editor and referees) (04 Apr 2018) by Piero Lionello

ED: Referee Nomination & Report Request started (04 Apr 2018) by Piero Lionello

RR by Anonymous Referee #1 (23 Apr 2018)

RR by Anonymous Referee #2 (24 Apr 2018)

Suggestions for revision or reasons for rejection

Review for the,

Assessment of peak tsunami amplitude associated with a great earthquake occurring along the southernmost Ryukyu subduction zone for Taiwan region

Yu-Sheng Sun, Po-Fei Chen, Chien-Chih Chen, Ya-Ting Lee, Kuo-Fong Ma and Tso-Ren Wu

Nat. Hazards Earth Syst. Sci

The manuscript presents an interesting application of tsunami modeling in the subduction zone of Taiwan, where the trench is orthogonal to the coastline. Authors assume a potential earthquake of magnitude Mw 8.15 breaking a fault of dimension 120 x 70 km2 with an average slip of 8.25 m. Several tsunami scenarios were simulated using stochastic random fields where the power spectrum of slip is assumed to falloff as k-2 at high wavenumber. The authors focus their analysis in the variability of the maximum tsunami wave height computed at several sites located around the Taiwan island. The histograms computed at each sites show a great variability, in particular at the eastern border of Taiwan, and these results are also compared against the maximum tsunami wave height computed assuming an uniform slip rupture scenario. Results reveal that assuming an uniform slip the maximum tsunami wave height underestimates a large number of predictions from nonuniform slip scenarios, but not at all sites. Also, the tsunami wave propagation shows a complex pattern of energy radiation, mostly due to bathymetry, but also to slip distribution. The subject is of general interest and with interesting results obtained in the near field, where the whole deformation pattern of an inverse fault affects the static displacement field of the coastal border along the eastern border of Taiwan island.

In this revised version, the inconsistencies of the random slip - seen on the first manuscript - were corrected and better clarified. Authors have taken into consideration all the comments and suggestions I did in the previous review, but I feel there are some minor points that can be easily corrected.

There is a major technical point that the authors can easily verify (see comments, Page 4, line 20; Page 5, line 6.), where they refer to convolution in the Fourier domain, but I think it is just multiplication in the Fourier space, this will not change their results, but I think it is better to precise the correct mathematical operation.

I apologize because I am not native English speaker, but from my little own expertise, I feel that the authors could better check the grammar and spellcheck (main text and some captions) for a better understanding.

Major and minor points

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Main text
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Page 1, Abstract, line 9. I suggest to change, "tsunami earthquakes" by "tsunamigenic earthquakes", to avoid any confusion with the "tsunami-earthquake" itself. I assume authors refer to any kind of earthquake that generates a tsunami (e.g. regular earthquakes, tsunami-earthquakes, etc.).

Page 3, line 16. Please, insert "vary" after (Delta_sigma).

Page 3, line 21. Change "is" by " are".

Page 3, line 22. I suggest to change "a definite" by "the assumed".

Page 3, line 27. I think a word is missing in the sentence "..can be transformed magnitude Mw", so, I will suggest, "...can be transformed to magnitude Mw".

Page 4, line 2. Please, insert the physical unit in the value of M0, I guess it is [dyne-cm].

Page 4, line 6. For better description, complete the word "temporal" by "spatio-temporal".

Page 4, line 13. I suggest to insert "The" before "k-2".

Page 4, line 15. For a better reading, I will suggest to change "self-similar introducing the...", "self similarity introduced the...".

Page 4, line 20. I think instead of "convolution in the Fourier domain" it should be, "multiplication in the Fourier domain", because the 2D Fourier spectrum of the random realization of slip is multiplied by k-2 in the Fourier domain beyond some characteristic wavelength.

Page 4, line 25. I suggest to replace "4" by "four".

Page 5, line 6. The "convoluting" operation is not correct. I will suggest to write something like, "by imposing a self-similar characteristic...".

Page 5, line 8. Correct "gird" by "grid".

Page 5, line 10. I will suggest to insert "shown in" before "Figure 1a".

Page 5, line 13. To complete the idea, I suggest to insert "faulting" before "mechanism".

Page 5, line 13-14. I think the sentence "In addition, the inversed slip distribution in study region is lack to do the analysis of Levy PDF" could be better executed. For instance, "There are not inverted slip models of past earthquakes in the study area to do the analysis of Levy PDF parameters.", or something like that.

Page 5, line 23. I will suggest to insert "the plate interface" before "..is locked..".

Page 5, line 24. To complete the idea, I suggest to add "over the whole fault plane" after "...uniform slip distribution.".

Page 7, line 27. Please, provide physical units to 1.024, m ?

Page 9, line 5. It is just a suggestion, but to better precise the idea, I suggest to modify the phrase "...is parallel the subduction zone.." by "..is parallel to the trench axis of the subduction zone", or something like that.

Page 9, line 6. Insert "along" before "these".

Page 9, Paragraph 2 and 3. To help the reader, I suggest to label the four NPPs (Nuclear Power Plants) in Figure 5, map on the right. The NPPs are labeled in Figure 2, but because authors discuss the NPP3, NPP2, etc, with respect to the PTA at different locations along the coast of Taiwan in Figure 5 again, it will be useful to see the label of each NPP in this figure.

Page 9, line 6. Wildest ?, or should it be "widest" ?. Please, clarify.

Page 9, line 7. Please, provide physical units to 1.63, m ?.

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Figures
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Figure 2. I will suggest to complement "(5x5 km2)", by "(5x5 km2 grid size)".

Figure 5. See my comments above (Page 9, Paragraph 2 and 3). It will be useful to label each NPP in the map on the right. Please, describe a little bit the map on the right in the caption. For instance, "Map of Taiwan with station locations and four NPP (yellow squares)."

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ED: Publish subject to minor revisions (review by editor) (15 May 2018) by Piero Lionello

AR by Yu-Sheng Sun on behalf of the Authors (07 Jun 2018) Author's response Manuscript

ED: Publish as is (24 Jun 2018) by Piero Lionello

AR by Yu-Sheng Sun on behalf of the Authors (02 Jul 2018) Manuscript

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Short summary

The maximum possible earthquake magnitude is M_w 8.15 with an average slip of 8.25 m in the southernmost portion of the Ryukyu Trench. One hundred slip distributions of the seismic rupture surface were generated by a stochastic slip model. The simulated results demonstrate that the complexity of the rupture plane has a significant influence on the near field for local tsunamis. The propagation of tsunami waves and the peak wave heights largely vary in response to the slip distribution.