Innovation Series: Advanced Science (ISSN 2938-9933, CNKI Indexed)

Study on Chain Reaction of Landslides in Special Strata under Extreme Rainstorm Conditions

Guodong Ai^1,*, Linbo Tang¹, Pengfei Li¹, Jianglin Li¹, Kelin Guo², Wentao Long¹, Yixuan Yang¹

¹ Mineral Resources Survey Institute of Hunan Province, Changsha, 410129,China

² Ecology Geological Survey and Monitoring Institute of Hunan Province, Changsha, 410119,China

Corresponding Author: Guodong Ai

Abstract: In July 2024, Typhoon “Gaemi” struck Zixing City, Hunan Province, triggering an extreme rainstorm with a maximum 24-hour rainfall of 642.5 mm, breaking the historical record in Hunan Province. The heavy rainfall induced a large number of geological disasters, mainly shallow landslides and slope debris flows, showing a significant “landslide --- debris flow --- flood” chain reaction characteristic. Based on the emergency investigation report of the “7·27” geological disaster in Zixing City and the post-disaster review report, combined with survey data from 706 geological disaster sites, this paper systematically analyzes the disaster mechanism and chain process of special strata such as granite and shallow metamorphic rocks under extreme rainfall conditions. The results show that special strata, with intense weathering and loose structure, are prone to high-altitude, shallow, and clustered landslides under short-term heavy rainfall; landslide masses mix with surface runoff during movement, transform into debris flows, further block river channels to form barrier lakes, trigger secondary flood disasters, and form multi-hazard compound chains. This paper reveals the causes of chain reactions from geological conditions, rainfall characteristics, topography, and human activities, and proposes an integrated disaster prevention and mitigation suggestion of “identification --- monitoring --- warning --- governance”, providing a scientific basis for disaster prevention and control under similar geological and climatic conditions.

Keywords: Extreme rainstorm; Special strata; Landslide; Chain reaction; Geological disaster; Zixing City

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