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In recent decades, there have been several extreme earthquakes around the world, with the 2008 Wenchuan earthquake resulting in the highest number of landslides and substantial deposition of loose material on steep terrain and deep gullies, thereby promoting post-earthquake debris flows. Our monitoring indicates that debris flows have become long-term threats for over a decade after the earthquake, and it is crucial to determine the long-term spatial and temporal changes of debris flows and the evolving influence of condition factors in the earthquake-affected area. Thus, we established a database of 1628 debris flow events occurring between 2000 and 2020 within the 31,627 km2 area affected by the Wenchuan earthquake. The database included information on the date of occurrence, GNSS (Global Navigation Satellite System) coordinate at the gully outlet, event washout volume, and scale level obtained from various sources. Post-seismic debris flow activity witnessed a significant increase, followed by oscillation with rainfall and gradual weakening. Using the average washout volume for each scale in different periods, we applied a grid calculation method to characterize the debris flow intensity (DFI) using the total debris flow volume of cells in different epochs to study the spatial and temporal evolution of debris flow activity. Thus, based on the DFI calculation, we introduced the certainty factor and Geodetector to determine the dynamic evolution of condition factors. Our results indicate that lithology, rainfall, and slope degree primarily controlled debris flows before the earthquake. However, coseismic landslides became the main promoting factor after the earthquake. As loose materials were consumed, hydrodynamic and topographic factors began to play a more significant role in controlling debris flows. During this process, the requirements for rainfall, slope degree, and terrain relief amplitude increased over time. Based on the annual volume of debris flows from 2000 to 2020, we developed a preliminary conceptual model, which indicated that post-earthquake debris flow activity can be categorized into three phases: active (2008–2013), unstable (2014–2033), and recession (2034–2045), with the debris flow activity anticipated to return to pre-earthquake levels by 2045. • Database of debris flow events that occurred in the Wenchuan earthquake affected area from 2000 to 2020 was established. • We use a grid calculation method to track the spatial and temporal evolution of debris flow activity. • The certainty factor and Geodetector were used to evaluate the dynamic evolution of the condition factors. • Debris flow activity increased sharply early after the earthquake, then oscillated with rainfall and gradually weakened. • Hydrodynamic and topographic factors began to influence debris flow activity more in 2014 than loose materials. [ABSTRACT FROM AUTHOR]

Surface deformation in continental interiors is typically coupled to processes at depth. However, in the Sichuan basin, east of the Tibetan Plateau, recent seismic data detect Neoproterozoic subduction and rifts, indicating long-term tectonic quiescence of the basement. The Sichuan basin is characterized by two episodes of weak extension and compression which influenced the architecture of the marine platform during Palaeozoic to Middle Triassic times. The weak extensional episodes occurred in the early Cambrian and late Permian, characterized by formation of intracratonic sags oriented at high angles to the basin margins, the early Cambrian Mianyang-Changning sag and the late Permian Kaijiang-Liangping sag. The formation of these sags was followed by weak compressional episodes that formed the Caledonian (Early Palaeozoic) Leshan-Longnvshi palaeo-uplift and the Mid. to Late Triassic Luzhou and Kaijiang palaeo-uplifts. These intracratonic sags and palaeo-uplifts show no genetic correlation in terms of geometry or inherited deformation. Subsequent evolution of the Sichuan basin was characterised by foreland basins controlled by the Longmenshan and Dabashan fold-and-thrust belts along the western and northeastern margins of the basin respectively. A large wedge-shaped body of strata was subsequently eroded, removing of 2.0-3.0 km of rock in the Cenozoic. The subsidence history of the Sichuan basin is characterized by an increase in subsidence rate due to the formation of the foreland basins and by a subsequent period of uplift and exhumation. We argue that structural decoupling occurred both between the sedimentary cover and the basement and between the multiple sedimentary sequences in the Sichuan basin. The Sichuan basin may thus represent a unique type of superimposed basin, as its evolution appears to have been controlled by deformation propagated from its peripheral orogens. This suggests a mechanism of basin architecture controlled by crustal deformation, rather than by deep lithospheric and mantle processes. [ABSTRACT FROM AUTHOR]