Discrete Element Method (DEM) modelling of the kinematic evolution of submarine landslides
Supervisors: Professor John Walsh, Dr Mike Long (UCD School of Architecture, Landscape & Civil Engineering), Dr Martin Schopfer and Koen Verbruggen (GSI)
Contact: john@fag.ucd.ie
Project Description:
Large‐scale gravitational collapse is a common mass wasting process in the evolution of the Earth’s continental margins, including the European Atlantic margin where numerous large‐scale submarine failures have been recognized from the southwest coast of Ireland to northern Norway. One of these events, the Storegga slide, affected an area of 95,000 km2 (i.e. larger than Ireland) and caused a tsunami which decimated Scottish coastal settlements and extended 80 km inland. Recognizing and understanding these extraordinary submarine landslide events is important because of: (i) the hazards they, and associated large‐scale tsunamis, present to people and crucial offshore/onshore infrastructure, (ii) the essential constraints they provide for general landslide processes, and (iii) their close relationship to offshore oil and gas reserves. This project will contribute to each of these issues by performing state‐of‐the‐art numerical modelling of submarine landslide processes, underpinned by excellent observational constraints (3‐D seismic and well data, supplemented by mechanical property data) from the Atlantic Margin.
This project will utilize Discrete Element Method (DEM) modelling to investigate the emplacement behaviour of large‐scale offshore landslide complexes. DEM simulates the deformation, faulting and fragmentation of rock masses, and is widely used in the mining and geotechnical industries: its application to the geosciences is on the increase and has been pioneered by UCD. The project will be approached in two phases, 2D and 3D (using proprietary software PFC‐2D© and PFC‐3D©). Key geometric and mechanical variables thought to influence the development of submarine landslides will be systematically examined including: [i] the interrelationship between, and the slopes of, the bathymetry and geological layering; [ii] the impact of erosion or oversteepening adjacent to potential emergent slide surfaces, [iii] mechanical properties and anisotropies of the slide body, [iv] frictional properties of potential slide interfaces, including the effects of pore fluid over‐pressure and dynamic friction.
An initial 2D phase will constrain the basic initiation and evolution of submarine landslides for the key variables. The more computationally robust and demanding 3D approach will develop further insight into the initiation and kinematic evolution of submarine landslides by considering lateral (out‐of‐plane) deformation of the landslide body. Emphasis will be given to a suite of models investigating the impact of key variables on the development and final architecture of natural submarine landslides. An additional set of models will attempt to reproduce the main features of a small selection of submarine landslides defined from the analysis of high quality multibeam, 3D seismic and well data.