Digital elevation models in the marine domain : investigating the offshore tsunami hazard from submarine landslides

Digital elevation models (DEMs) of seabed relief are now commonly available at a number of scales. On a global scale three-dimensional (3D) relief maps of the ocean floor are derived from satellite gravity measurements validated by single-beam echo soundings. On a smaller, more local, scale, the development of multibeam bathymetric mapping technology provides detailed seabed data from which DEMs are derived. Over the past 30 years multibeam bathymetry has replaced single-beam echo soundings as the main tool used to map the sea floor. Multibeam bathymetry has revolutionized our ability to interpret seabed morphology. It has the capability to provide complete seabed coverage and gives a 3D visualization of the seabed not previously available. DEMs derived from multibeam are comparable to those on land. One aspect of the improved seabed visualization is in mapping marine geohazards. Here three DEMs, from Papua New Guinea, Hawaii and the Indian Ocean, are presented. These DEMs have been used to investigate submarine seabed failure and volcanic flank collapse in the context of their tsunami hazard. For these three areas the DEMs contribute to an improved interpretational capability in marine geohazards. In addition, the DEMs underpin newly developed modelling methodologies of landslide-generated tsunami.