Some mudslide movement patterns

A study has been made of the mechanisms of movement in a mudslide and the interrelationships between the controlling variables. Detailed monitoring has been conducted on a mudslide developed in the Wealden Beds, a Cretaceous mudrock. The parameters which govern mudslide instability have been continuously monitored using electronic datalogging techniques. Slip can be divided into four components: small ‘multiple’ (stick slip) movements which are grouped temporally; gradual or ‘graded’ slip within defined temporal limits; rapid ‘surge’ events which occur over a short time interval and involve large displacements and unexplained ‘random’ movements. Each of these four components occurs with varying frequency and at different times in the seasonal record. Slip is usually separated by periods of little or no change. Each component of mudslide movement displays characteristic patterns of pore water pressure change.