The Calculation Method for the Volume of Landslides and Dammed Lake Sediments Triggered by a Strong Historical Earthquake in the Loess Plateau: A Case Study of Qiuzigou, Gansu Province, Northwest China

• 作者: CHEN Lize DU Peng LI Wenqiao TIAN Qinjian XU Yueren
• 来源期刊: 中国地震研究（英文版）
• 年，卷（期）: 2020,（4）
• 所属期刊栏目: Landslide Case Study
• 页码范围: 580-598
• 页数: 19页
• 语种: 英文
• DOI: 10.19743/j.cnki.0891-4176.202004004

摘要

The quantitative calculation of the volume of large earthquake-triggered landslides and related dammed lake sediments is of great significance in the study of secondary disasters and focal parameters of strong historical earthquakes. In this study, the dammed lake induced by Qishan M7 earthquake ( Lingtai County, Gansu Province, Northwest China) is selected as the research object. Based on the information collected from the 4 boreholes in the dammed lake area, we further take advantage of the low-level Unmanned Aerial Vehicle ( UAV) photogrammetry and the morphology recovery method, to calculate the volume of the dammed lake and landslides, respectively. Finally, major conclusions are obtained as follows:① the AMS-14 C age at the bottom of the Qiuzigou Dammed Lake sediments is 2890 ± 30 BP, which coincides with the 780 BC Qishan earthquake;furthermore, the Qiuzigou Landslides seem to have been triggered by the earthquake, forming an enclosed dammed lake deposition environment after the upstream sediments accumulate;② the Qiuzigou landslides are opposite-sliding landslides that have blocked the river valley; in detail, landslide volumes at the right and left banks are 235 × 104 m3 and 229 × 104 m3 , respectively. The length of the dammed lake is 2. 6 km, with a thickness of approximately 43 m near the landslides, and the total sedimentary volume is 573 × 104 m3;③the erosion rate of Qiuzigou Landslide Dammed Lake is 0. 44 mm/a, the accumulation rate is 15. 05 mm/a, and the soil erosion modulus is 593 t/( km2/a) , characterized as slight erosion. Quantitative research on the formation of landslides and dammed lakes from strong historical earthquakes is vital for increasing our understanding of the vibrational characteristics and surface action processes of these types of earthquakes.