Landslides triggered by the 2015 Mw 6.0 Sabah (Malaysia) earthquake: inventory and ESI-07 intensity assignment
- Università dell’Insubria, Dipartimento di Scienza e Alta Tecnologia, Como 22100, Italy
- Università dell’Insubria, Dipartimento di Scienza e Alta Tecnologia, Como 22100, Italy
Abstract. On 4 June 2015, a Mw 6.0 earthquake occurred in the Sabah region (Malaysia), triggering widespread landslides along the slopes of Mt. Kinabalu. Despite the moderate magnitude, the Sabah earthquake was very efficient in triggering landslides: here I provide an inventory containing 5198 slope movements, mapped in an 810 km2-wide area. I investigate earthquake intensity using the Environmental Seismic Intensity (ESI-07) scale, which is a macroseismic scale based exclusively on earthquake environmental effects. The epicentral ESI-07 intensity is assessed at IX, considering the dimension of the area affected by secondary effects; such figure agrees well with a dataset of global earthquakes.
I estimate the volume of individual landslides using area-volume scaling laws, then I assigned an ESI-07 intensity to each mapped landslide. I document that the selection of a given area-volume relation has a minor influence on the ESI-07 assignment. Then, I compare ESI-07 values to landslide density and areal percentage on a 1-km2 grid; such parameters are widely adopted in the description of earthquake-triggered landslide inventories. I argue that their integration with the ESI-07 scale may provide an effective way to compare earthquake damage on a variety of spatial and temporal scales. The methodological workflow here illustrated is useful in joining the scientific communities dealing with the realization of earthquake-triggered landslide inventories and with ESI-07 assignment; I believe this effort is beneficial for both the communities.
Maria Francesca Ferrario
Status: final response (author comments only)
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RC1: 'Comment on nhess-2022-69', Anonymous Referee #1, 01 Apr 2022
Database construction and distribution analysis of landslides triggered by large earthquakes are of great significance. In this manuscript, landslides triggered by a large earthquake in 2015 was taken as the object, and a relatively detailed and complete landslide distribution map was established. Then, the distribution law of landslides was analyzed, and the comparison with other large earthquake-triggered landslides was carried out. I have only one suggestion, and that is that it looks like this study is missing a scientific discussion section, although there is a section titled Results and Discussion. In fact, it's mostly results, not discussions. It is recommended to separate the two and discuss from more aspects, such as data, methods, results, etc., and compare with other earthquake cases and previous work to analyze the advantages and disadvantages of this work. In addition, there is a need to have a prospect for future work.
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AC1: 'Reply on RC1', Maria Francesca Ferrario, 20 Jun 2022
I wish to thank the anonymous reviewer for his/her thoughtful comments, which helped in improve the quality of the manuscript. Here I provide a point-to-point answer to all the comments raised by reviewer 1. Original comments are shown in italic, while my answer is in plain text.
RC1: Anonymous Referee #1, 01 Apr 2022
Database construction and distribution analysis of landslides triggered by large earthquakes are of great significance. In this manuscript, landslides triggered by a large earthquake in 2015 was taken as the object, and a relatively detailed and complete landslide distribution map was established. Then, the distribution law of landslides was analyzed, and the comparison with other large earthquake-triggered landslides was carried out. I have only one suggestion, and that is that it looks like this study is missing a scientific discussion section, although there is a section titled Results and Discussion. In fact, it's mostly results, not discussions. It is recommended to separate the two and discuss from more aspects, such as data, methods, results, etc., and compare with other earthquake cases and previous work to analyze the advantages and disadvantages of this work. In addition, there is a need to have a prospect for future work.
Agreed. I now separate Section 4 (results) from Section 5 (discussion). In the results, I describe the spatial distribution of landslides (Section 4.1) and the scaling relations among LND, LAP and ESI-07 intensity (Section 4.2).
The new structure of the Discussion section is as follows:
- 5.1 From the 2015 Sabah earthquake toward a generalization. Here I discuss the results obtained on the Sabah earthquake, and specifically the relations among LND/LAP and ESI-07, by comparing them with the 2008 Wenchuan earthquake. This section should be the ground on which a wider study can be realized, investigating all the existing earthquake-induced landslide inventories, to obtain more reliable empirical relations.
- 5.2 Comparing the 2015 Sabah case study with worldwide data. This is the former Section 4.3, where I put the Sabah case history in a broader context, investigating the distribution of number of landslides and affected area with respect to earthquake magnitude.
- 5.3 Challenges and prospect for future work. I added this section, summarizing the challenges due to input data and methodological steps. I also stress what I believe is the main novelty of the current work, that is the derivation of scaling relations among LAP/LND and ESI-07 intensity.
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AC1: 'Reply on RC1', Maria Francesca Ferrario, 20 Jun 2022
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RC2: 'Comment on nhess-2022-69', Vipin Kumar, 30 Apr 2022
Comments on the research article (NHESS-2022-69):
Author aims to elaborate spatial patterns of earthquake (2015 Mw 6.0 Sabah (Malaysia) triggered landslides using Landslide Number Density (LND) and Landslide Area Percentage (LAP). Author further applies the Environmental Seismic Intensity (ESI) scale-2007, considering epicentral intensity of IX (based on landslide affected area). The ESI-07 is used by utilizing the volume of landslides, which is determined using published landslide Area-Volume scaling relationships. The article is mostly well written except few clarifications/elaborations that will make potential readers having diverse backgrounds more interested.
Comments:
- Author needs to include both pre- earthquake landslide (if any) and post-earthquake landslide inventory of the study area to effectively demarcate the “co-seismic landslide affected area”. This affected area is crucial in view of the utilization of ESI-07 scale.
- Author also needs to recalculate the LND and LAP in view of the possible changes in the inventory caused by exclusion of pre-earthquake landslides.
- Though it might be difficult to classify 5198 landslides based on type, effective usage of the landslide area-volume (A-V) scaling relationships require type classification. Most of these A-V scaling relationships have been obtained in specific geological and/or climatic settings and have been subjected to defined hillslope material. Notably, Larsen et al. (2010), who used an inventory of >4000 landslides, observed that γ varies based on hillslope material. Further, why did the author include only 6 of the many published landslide A-V scaling relationships?
- Earthquakes generally result in many rock fall type landslides, as the author also showed in Fig. 2c. Author could have included some A-V relationships that have been proposed for rock falls.
- AC2: 'Reply on RC2', Maria Francesca Ferrario, 20 Jun 2022
Maria Francesca Ferrario
Maria Francesca Ferrario
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