Causes and Consequences of Giant Submarine Landslides, New Zealand

Submarine landslides are increasingly recognised as a major geological hazard, both to subsea infrastructure and coastal communities. Associated tsunami hazards in particular cause a major threat to local populations, with over 250k fatalities caused by tsunamis globally in the last 20 years. Landslide tsunamis can have exceptionally high wave heights and runups - tens to hundreds of metres near the source area - but are poorly understood in terms of triggering mechanisms, and wave characteristics.
New Zealand, which sits on an active plate boundary, is particularly prone to tsunamis, with events exceeding 1 m wave height occurring every 10 years on average. This includes waves generated by a variety of sources, including seabed rupture during earthquakes, cliff collapse and submarine landslides. There is also evidence for numerous giant submarine landslides, which likely caused catastrophic ‘mega-tsunamis’ but which have not occurred since historical records began. These include the giant (3000 km2) Rotorua landslide which occurred ~170 ka. The preconditioning and triggering mechanisms for such events are still poorly understood, and the consequences of such an event occurring in the future are also not well constrained.

For this project, the student will use an extensive 2D and 3D seismic dataset covering the entire continental shelf and slope of New Zealand, as well as an extensive set of exploration wells acquired by oil and gas companies, to identify and map submarine landslides in the offshore basins of New Zealand. Details of landslide size (area, thickness volume) and morphometric characteristics will allow the flow process to be constrained, and provide critical inputs for numerical modelling of landslides and tsunami propagation and runup. These models will be built using state-of-the-art NHWave and FUNWAVE-TVD software. Well data will provide critical inputs on the physical properties of the landslides and failure planes, and age control to constrain the frequency of events in different regions.

This exceptional database will be used to address a number of unresolved questions regarding landslide preconditioning, including: (1) are slopes preconditioned for failure by weak contourite layers? (2) Does hydrate dissolution during warming events promote failure, and at what timescales? (3) Do high sedimentation rates in submarine delta fronts promote failure? In addition, the numerical models generated will provide a range of tsunami runup heights and inundation, which can be tested by looking for evidence of palaeo-tsunamis in Quaternary sediments onshore.

This project builds on the existing expertise in marine geohazards in IGE and partners at the BGS in the Lyell Centre, and particularly developing concepts established during a number of recent and ongoing projects on landslide tsunami hazards. The student will be encouraged to build a network of collaborators in the BGS as well as Heriot-Watt, taking advantage of the relationship developed between the two organisations through the Lyell Centre, where they will be based. There may also be opportunities for the student to work on future projects funded by the Global Challenges Research Fund (GCRF) an area of major strategic growth for UK national research and the university.

Candidates should have a good BSc/MSc degree in Geology/Earth Sciences and experience or interest in coding/numerical modelling.

To make an application, please visit the website.