Natural Hazards

, Volume 66, Issue 2, pp 557–575

Potential collapse of the upper slope and tsunami generation on the Great Barrier Reef margin, north-eastern Australia

Authors

    • Departamento de Estratigrafía y Paleontología, Facultad de CienciasUniversidad de Granada
    • Geocoastal Research Group, School of GeosciencesUniversity of Sydney
  • Jody M. Webster
    • Geocoastal Research Group, School of GeosciencesUniversity of Sydney
  • Robin J. Beaman
    • School of Earth and Environmental SciencesJames Cook University
Original Paper

DOI: 10.1007/s11069-012-0502-0

Cite this article as:
Puga-Bernabéu, Á., Webster, J.M. & Beaman, R.J. Nat Hazards (2013) 66: 557. doi:10.1007/s11069-012-0502-0

Abstract

Analysis of high-resolution multibeam bathymetry and seismic profiles in the Noggin Passage region, north-eastern Australia, has identified a small area (Noggin block) in the upper-slope offshore Cairns that may potentially collapse and generate a tsunami wave. The Noggin block extends from 340 to 470 m depth covering a roughly circular (2.4 km long and 3.7 km wide) area of about 5.3 km2. The well-defined margins of the block correspond to different bounding seabed features. These features include steep headscarps, small landslides and a group of aligned circular pockforms up to 500 m wide and 20 m deep. Slope stability simulations indicate that the Noggin block is stable under normal present-day gravitational conditions on the upper slope. However, block failure may result under external loads, such as those produced by earthquakes. Failure modelling shows that critical peak horizontal accelerations of 0.2–0.4 g could lead to the collapse of the Noggin block. In north-eastern Australia, these acceleration values would involve earthquakes generated at short hypocentral distances and short periods. The collapse of the potential sediment slide mass of about 0.86 km3 (162 m average thickness) may lead to the formation of a landslide-generated tsunami wave. Semi-empirical equations indicate the collapse of this mass would yield a 7–11-m high three-dimensional tsunami wave. These waves could reach an estimated run-up height at the coast of 5–7 m. Our first-order approach highlights the potential consequences for nearby coastal communities, the need for better sediment characterisation in the study area, and the systematic identification of other areas prone to slope failures along the Great Barrier Reef margin.

Keywords

Slope failure Tsunami run-up Slope stability simulations Coastal hazard Landslide Submarine canyons

Copyright information

© Springer Science+Business Media Dordrecht 2012