How do ancient mass-transport complexes influence subsequent failure events? A case study from the Kangaroo Syncline, offshore NW Australia

Nan Wu , Christopher Aiden-Lee Jackson , David Hodgson, Harya Dwi Nugraha , Fa Guang Zhong

Mass-transport complexes (MTCs) are common features in all continental margins. In some passive margins, accumulations of stacked MTCs indicate repeated slope failure, which raises the question of whether MTC emplacement may influence or even pre-condition, subsequent slope failures. Here, we use 3D seismic reflection data from the Kangaroo Syncline, NW Australia, to investigate how pre-existing MTCs can prime subsequent failure events. We show that: i) lithological heterogeneity present within a sedimentary succession due to MTC emplacement can dictate where subsequent slope failure occurs; ii) relief along the top surface of an MTC controls the transport pathway and stratigraphic architecture of a subsequent MTC; iii) topography created by a buried MTC can enhance the erosive ability of subsequent slope failure events; iv) pre-existing MTCs headwall scarp can drive a cascading effect and influence multiple subsequent slope failures; and v) the thickness distribution pattern of buried MTCs could provide a mechanism for predicting the depocentre of future slope failure events. Buried MTCs have profound effects on the location, nature, geometry, and hazard potential of future slope failures. Therefore, investigating the interaction between multi-stacked MTCs has significant implications for geohazard impact assessment.