Author: Puga-Bernabéu, A., Thran, A.C., Webster, J.M., Beaman, R.J., López-Cabrera, J.F.
Publication: The north-eastern Australia margin: Submarine landslide characterisation and tsunamigenic potential in a mixed carbonate-siliclastic setting, International Sedimentological Congress 2018, 13-17 August 2018. International Association of Sedimentologists (IAS), Quebec, Canada.
The socioeconomic importance of submarine landslides is related to their tsunamigenic potential with far-reaching effects and ability to damage seabed and coastal infrastructure and take human lives. Submarine landslides are ubiquitous features on the slopes of continental margins worldwide, but case studies from modern mixed carbonate-siliciclastic margins are scarce. The north-eastern Australia margin is the largest mixed carbonate-siliciclastic province in the world and hosts the iconic Great Barrier Reef (GBR).
We describe the main geomorphologic characteristics of four representative examples of submarine landslides along the GBR margin and evaluate their tsunamigenic potential and impact on adjacent coasts at the time of inception. Landslide-generated tsunamis were simulated using the source component TOPICS within the Geowave model, a fully nonlinear, fully dispersive, 4th-order Boussinesq numerical model.
Study examples from north to south are:
(1) The Ribbon Reef Slide, the largest in the northern region. It extends over 100 km2 from ~2000 m depth down to 2260 m, and remobilized at least 1 km3 of slope material. The depositional area shows a distinctive suite of cohesive blocks up to 2 km long and 40 m in height, with a runout length of ~16 km;
(2) The Gloria Knolls Slide, which is the largest landslide complex on the margin. This landslide forms a 20 km along-slope and 8 km across-slope indentation in the margin that remobilized ~32 km3 of sediment, leaving a steep headscarp up to 830 m in height. The main depocentre comprises a cluster of km-scale knolls and over 70 smaller debris blocks;
(3) The Bowl Slide is a landslide complex indented in the shelf-edge paleo-Burdekin river delta and extends down to >1000 m. It comprises three main headscarps at 100-130 m, 200-250 m and 450-600 m. Collapsed material forms a 200 km2 cone-shaped debris field that extends over 16 km from the source area;
(4) The Viper Slide is a shallow-water (90-250 m), small (~19 km2, 0.025 km3) and 7 km-wide shelf-edge slope failure that left a cone-shaped blocky deposit 5.5 km long and ~25 m thick.
Simulations indicate that these landslides are capable of producing 2-20 m tsunami waves at the failure source. However, maximum run up heights at the coast are considerably reduced due to the high buffering capacity of the GBR to these slope failures.