Characteristics of losses of geological disasters and major disaster types in Liangshan Prefecture, Sichuan Province

Due to active tectonics, topography, and river dynamics, Liangshan Prefecture is highly susceptible to geological disasters in Sichuan Province. In order to find out the developmental patterns, characteristics, and prevalent disaster modes of geological disasters in Liangshan Prefecture, this paper uses data collection, mathematical statistics, field investigation and other methods to conducted a comprehensive analysis of geological disaster data, disaster situations, and major sudden geological disaster cases in Liangshan Prefecture. The results show that the primary geological hazards in Liangshan Prefecture are landslides and mud-rock flows. The landslides are mainly medium and small scale soil landslides, and the mud-rock flows are mainly medium and small scale gully mudflows. Over the recorded period, Liangshan Prefecture experienced 23 geological disasters resulting in more than 10 fatalities. Between 2006 to 2020, 46 geological disasters occurred, mainly in the forms of debris flow. This paper identifies and refines seven typical geological disaster modes in Liangshan Prefecture. Notably, red bed landslides, prone to softening and disintegration in water with poor self-stability, constitute a significant landslide type. Reactivation of ancient landslides, widely distributed in the region, is triggered by human activities, river erosion, and other factors. Reservoir bank landslides are prevalent in the reservoir areas of Muli County, Butuo County, and Ningnan County, posing risks due to fluctuating reservoir water levels. There are many hidden dangers of bank collapse due to the influence of reservoir water level, and the slope Coal-bearing landslides are prominent in the southern coal measure stratum area, induced by unsustainable mining practices. Slag-type debris flow is one of the main types of debris flow in Liangshan Prefecture. The unreasonable stacking of slag, waste rock and tailings provides rich material sources for debris flow disasters. Liangshan Prefecture frequently experiences forest fires, and the burned land is easy to induce post-fire mud-rock flow after heavy rain. When the landslide disasters occurs in the upper reaches of gullies with strong tectonic activity and steep mountain potential, it is easy to rush out along the gully, blocking the river and forming a chain disaster. The research results can provide data support and scientific insights for disaster prevention and mitigation in Liangshan Prefecture.