Vegetation-landslide nexus and topographic changes post the 2004 Mw 6.6 Chuetsu earthquake

Ground shaking on steep slopes often triggers numerous landslides, which dramatically modify the landscape and have long-term effects on vegetation dynamics. However, we still have a limited understanding of the quantitative topographic evolution and the duration of post-seismic impacts on the landscapes due to the lack of longterm consistent observation, especially in low-elevation mountain regions. To address this issue, we used highresolution pre-and post-earthquake DEMs to investigate topographic changes, as well as multi-period and multiscale remote sensing images to analyze the post-seismic landslides and vegetation recovery in the sites affected by the Mw 6.6 2004 Chuetsu earthquake, Japan. Using a vegetation recovery rate (VRR) time series from 2004 to 2021, we examined the decaying tendency of post-seismic landslide activities and predicted the vegetation recovery rate. Our findings indicate that the Chuetsu earthquake mostly steepens and roughens the terrain in lowelevation areas. The changes to slope aspects are associated with coseismic lateral displacement. The vegetation damage area accounted for 87.98 % of the entire area after the earthquake, and the VRR reaches 85.55 % by June 2021. The number of active landslides decreased to 14.45 % after 15 years. Meanwhile, we predict that vegetation recovery areas will be restored to pre-earthquake levels in 2024, and the landslide activity rate will decrease by less than 1 % in 2026, indicating a stable hillslope devoid of debris flows in the future.