During a storm the ground becomes saturated with water, reducing the soil's cohesion. As strong winds move the top of the tree, the force is transferred by the stem, acting as a lever, to the roots and the ground begins to move.

This mechanism works best with spruce trees (genus Picea), with their almost disc-shaped root system growing in the uppermost layers of the soil. A 0.5-inch thick root can sustain almost 350 pounds before it breaks, enough force to move the ground and smaller boulders.

這兩段說明這個現象

有兩個重要條件: 1. 充滿水分的土地，降低了土壤的凝聚力 ; 2. 高大而且具有淺而廣的根系植物(此例為雲杉) 然後強風一吹樹梢，因為槓桿的關係，地面的皮層就被拉動