According to the surveying data, the slope movement at the North pit wall of West Sub pit has been moving with an average rate of about 1.16 cm/day (April 24th, 2015) and South pit wall of West Sub pit has been moving with an average rate of about 0.94 cm/day. Moreover, the inclinometer data indicated movement in southeast direction, which conform to survey data.
The result from dropping a plummet method indicates the weak layer, which is clay that below coal seam E1, However, there will be continuous monitoring.