Abstract
On August 7, 2021, a disastrous rainfall-induced landslide occurred at Mt. Silabaku in the Yusui Stream source area, Taiwan. The huge deposits from the Silabaku landslide severely damaged the Minbaklu Bridge, and minor collapses in the Yusui Stream disrupted the only major road, Expressway No. 20. More than 400 residents from the three adjacent villages were stranded for 19 days in the mountainous area. The analysis of rainfall data, seismic records, topographic and geologic data, and historical orthoimages of the slope conditions, landform evolution, and current status of the Silabaku landslide revealed that the landslide resulted from slate avalanche induced by heavy rains, with local failures during Typhoon Morakot in 2009. Based on the high-resolution topographic data of light detection and ranging and an unmanned aerial vehicle, the debris deposits accumulated along the Yusui Stream were estimated to be above 8 million m3. In addition, a fan volume of 2 million m3 changed the flow line of the Laonong River, and the thick deposits pose a considerable threat to the safety of the nearby villages and infrastructures.
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Acknowledgements
The authors acknowledge the Institute of Earth Science of Academia Sinica, Taiwan, for the broadband seismic waveforms; the Forestry Bureau, Council of Agriculture, Executive Yuan, Taiwan for providing LiDAR data; and the Central Geological Survey, Taiwan for LiDAR data establishment. We used SPOT satellite images from the Center for Space and Remote Sensing Research, National Central University, Taiwan, using the Web Map Tile Service (Fig. 3). The aerial and satellite (Pleiades) images in Figs. 3 and 4 are from BigGIS (https://gis.swcb.gov.tw/), the Soil and Water Conservation Bureau, Taiwan. More information on the GeoPORT working group can be found at https://myweb.ntut.edu.tw/~ccchiu/geoport/index.html.
Funding
This research was supported by the Ministry of Science and Technology (MOST), Taiwan (grant no. MOST 110–2124-M-027–001, MOST 110–2116-M-239–001-MY2), and the Soil and Water Conservation Bureau, Taiwan (grant no. SWCB-110–031). The deployment of temporal seismic networks was funded by MOST (MOST 110–2636-M-009–001) and AS (AS-TP-109-M08).
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Yang, CM., Chao, WA., Weng, MC. et al. Outburst debris flow of Yusui Stream caused by a large-scale Silabaku landslide, Southern Taiwan. Landslides 19, 1807–1811 (2022). https://doi.org/10.1007/s10346-022-01888-6
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DOI: https://doi.org/10.1007/s10346-022-01888-6