<p>Large rockslides can induce catastrophic air blasts, significantly expanding the scope of disaster impact. To better understand the evolution and key control factors of air blasts, this study uses the Niumian Valley rockslide—the largest rockslide triggered by the 2008 Wenchuan earthquake—as a case study. A numerical method combining computational fluid dynamics (CFD) and discrete element method (DEM) was employed to simulate the dynamic process of the rockslide and the resultant air blast. Control experiments were conducted on rock masses of three different strengths to examine the influence of rock strength and topography on the dynamic characteristics of air blasts. The results indicate that (1) high-strength rock masses can generate more significant air blasts within a localized range; however, the range of disasters caused by air blasts from low-strength rock masses is even larger. (2) High-strength rock masses are primarily influenced by air resistance, which suppresses sliding, whereas low-strength rock masses are primarily affected by air-layer lubrication, which promotes sliding. (3) Topography plays a key role in the formation of air blasts, and significant air blast disasters are likely to occur near the collision points of barrier terrain and steep scarp bottoms, as well as near the exit of valley terrains.</p>