During which season is mass movement considered to be a greater threat?

Mass movement, also known as landslides or soil erosion, is significantly influenced by environmental conditions, particularly moisture levels in the soil. During a wet spring before vegetation is growing, the soil tends to be saturated with water. This saturation increases the weight of the soil and the likelihood of it losing cohesion. When there is excessive rainfall, the water acts as a lubricant, reducing friction and making it easier for the soil to slide down slopes.

In contrast, other seasons, such as a dry summer or a dry autumn, often result in drier soil conditions which can lead to a reduction in mass movement events. During a wet spring when vegetation is still dormant, there isn’t enough root structure to stabilize the soil, heightening the risk of mass movement. Vegetation increases soil stability because roots bind the soil together, but when it's absent, the susceptibility to landslides or other forms of mass movement is considerably greater. This combination of saturation, lack of vegetation, and potentially steep slopes makes the phase right before vegetation fully develops during the wet spring a particularly hazardous time for mass movement events.