Failure mechanism of a mudstone slope embedded with steep anti-dip layered sandstones: case of the 2016 Yanchao catastrophic landslide in Taiwan
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On September 28, 2016, the torrential rainfall carried by Typhoon Megi induced a catastrophic mudstone landslide in the Yanchao District of Kaohsiung City, Taiwan. The total volume of the sliding mass was approximately 8700 m3, which blocked an industrial road and displaced a duplex house in the downslope, leading to three deaths. Unprecedentedly, the 2016 Yanchao landslide was large and quickly raised public awareness regarding the possibility of large landslides that could occur in the nearby mudstone areas. Based on field surveys, topographic and geological maps, unmanned aerial vehicle (UAV) photography, and remote-sensing imagery, the failure mechanism of the 2016 Yanchao landslide is described in this study. The results revealed that steep anti-dip layered sandstones embedded with the mudstones play a critical role in large, rainfall-induced landslides. In the case of Yanchao landslide, the bedding joint between two formations was associated with the runoff infiltrating the low permeability mudstone. The kinematic process of the landslide consisted of two phases: a circular failure in the lower formation (alternation of mudstone and sandstone) and the subsequent regressive failure in upper formation (thick sandstone interbedded with mudstone). This study discloses the role of steep anti-dip layered sandstone influencing mudstone slope failure behaviors and presents a preliminary guide for assessing large, rainfall-induced landslides in mudstones. The results could also provide useful information for calibrating the numerical modeling of large landslides that may occur in the mudstone area in the future.
KeywordsMudstone slope Steep anti-dip layered sandstones Landslide Failure mechanism
The authors appreciate the assistance of the Sinotech Engineering Consultant, Inc. in providing data.
This work was supported by the Ministry of Science and Technology (MOST), Taiwan: Grants 104-2625-M-390-001 and 105-2625-M-390-001. The first and second authors were supported by the Young Scholar Fellowship Program by the MOST: Grant 107-236-E-006-003. The research was, in part, supported by the Higher Education Sprout Project, Ministry of Education, Taiwan, ROC, Headquarters of University Advancement to the National Cheng Kung University.
- Chen, S.T., 1994. The characteristics of the engineering geology of the mudstones(shales) in southwestern Taiwan. Sino-Geotechnics. 48, 25–33. https://doi.org/10.30140/SG.199412.0002 (In Chinese)
- Yang, C.-J., Lin, J., Cheng, Y.-C., 2014. Rill erosion of mudstone slope-a case study of southern Taiwan, in: EGU general assembly 2014, held 27 April - 2 may, 2014 in Vienna, Id.4598Google Scholar
- Yang C-J, Lin J, Cheng Y-C (2016) The process and mechanism of rill development on mudstone slope a case study in Taiwan. J Geogr Sci 81:27–42. https://doi.org/10.6161/jgs.2016.81.02 (InChinese). http://www.airitilibrary.com/Publication/alDetailedMesh?DocID=04945387-201606-201608010002-201608010002-27-42#Summary