Which of the following types of mass movements are categorized as rapid movements? 1. Creep 2. Mudflow 3. Solifluction 4. Slump Select the answer using the code given below.

Mass movements are classified based on their velocity into slow and rapid categories. Creep is defined as an extremely slow, almost imperceptible downslope movement of soil and rock debris [1]. Solifluction is also categorized as a slow movement, involving the downslope flow of soil mass saturated with water, typically in periglacial environments. In contrast, mudflows are rapid, fluid movements of debris and water, often occurring after heavy rains. Slumps are categorized as relatively rapid and perceptible movements where rock debris slips with a backward rotation along a curved rupture surface [4]. While some sources note slumps can vary in speed, standard geomorphological classifications, including NCERT and major textbooks, group slumps and mudflows under rapid movements compared to the imperceptible nature of creep and solifluction [2]. Therefore, mudflow and slump are the rapid movements among the options.

Sources

1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 8: Natural Hazards and Disaster Management > 8.36 Environment and Ecology > p. 43
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Slow Movements > p. 86
3. [4] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Landslides > p. 88