Similarities and Differences in Triggering Conditions of Typhoon Rainstorm-Induced Clustered Shallow Landslides in Semi-humid Northern and Humid Southern China

Abstract Clustered shallow landslides induced by typhoon rainstorms are common in humid southern China, but they are rare in the semi-humid north. However, Typhoon Doksuri in 2023 triggered more than 18000 shallow landslides in the Northeastern Taihang Mountains. The triggering conditions of typhoon rainstorm-induced clustered shallow landslides vary among different climatic zones. It is necessary to understand the regional similarities and differences in triggering conditions for developing adaptive landslides early warning systems. However, studies on semi-humid northern regions remain limited. To address this gap, we conducted a comparative investigation in two typical study areas: the semi-humid Northeastern Taihang Mountains and the humid Zixing Hills, highlighting the similarities and differences in the landslide triggering conditions. The results show that: (1) In both regions, landslides are mainly controlled by precipitation-elevation coupling and are concentrated at elevations of 300–1,000 m; (2) In the Northeastern Taihang Mountains, landslides occur on gentle slopes with topographic position index (TPI) ranging from −7 to 9 under the influence of precipitation coupling, while in the Zixing Hills, landslides are concentrated in areas with moderate relief (20–35 m) under the effect of precipitation; and (3) Vegetation has different effects: in the Northeastern Taihang Mountains, landslides occur in areas with sparse vegetation (normalized difference vegetation index, NDVI < 0.4), while in the Zixing Hills, they occur in areas with dense vegetation (NDVI = 0.79–0.84). These findings could help advance the regionally adaptive landslide hazard early warning systems.