Landslide Investigation Results in Sapa Town, Lao Cai Province, Vietnam in December 2019
Nguyen Van Thang*1,, Go Sato*2, Akihiko Wakai*1, Hoang Viet Hung*3, Nguyen Duc Manh*4, Takashi Kimura*5, Takanari Yamasaki*2, Shinichi Tosa*6, Kazunori Hayashi*7, Akino Watanabe*1, Takatsugu Ozaki*1, Nobuyuki Asai*8, and Nanaha Kitamura*1
1-5-1 Tenjin, Kiryu, Gunma 376-8515, Japan
*2Teikyo Heisei University, Tokyo, Japan
*3Thuyloi University, Hanoi, Vietnam
*4University of Transport and Communications, Hanoi, Vietnam
*5Ehime University, Ehime, Japan
*6Japan Conservation Engineers & Co., Ltd., Tokyo, Japan
*7Okuyama Boring Co., Ltd., Miyagi, Japan
*8Department of Mathematics, Faculty of Science and Technology, Tokyo University of Science, Tokyo, Japan
Every year, especially in the rainy season, landslides occur quite often in Lao Cai – a northern mountainous province of Vietnam. Specifically, in the year 2019, several landslides were observed to occur near the Sapa Ancient Rock Field in Hau Thao commune, Sapa town, Lao Cai province. In December 2019, a landslide investigation was conducted to examine the mechanism and possible causes of the landslides. Besides that, as the landslide distribution in this area is still unclear, this study will also aim to show the landslide denseness in a 700 m × 700 m square map as well as survey results in 2019 of two main landslides in such map. According to the survey, the landslide is the main phenomenon of geomorphological development in this area, being a combination of multiple different landslides with varying sizes and dissimilar triggers. The first survey landslide is about 50 m wide and 350 m long and has still been going on in recent years, with annual horizontal displacement being around 0.8 m. Meanwhile, the second one is a typical flash-landslide caused by rainfall. Despite being quite small in scale, about 15 m × 40 m, its characteristics indicate a dangerous implication in the future. This information will be the basis for further ongoing studies.
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