Probabilistic tsunami hazard assessment: quantifying uncertainty in landslide generated waves
File(s)
Author(s)
Snelling, Branwen
Type
Thesis
Abstract
Landslide generated waves (LGWs) have many associated uncertainties that need to be ac- counted for during a hazard analysis. The work presented in this thesis developed and applied numerical modelling techniques to investigate and quantify these sources of uncertainty.
Firstly, to model the LGW source as a deformable slide, a smoothed particle hydrodynamics (SPH) simulator was improved and adapted. The simulator was tested using lab scale bench- marks and an idealised full scale LGW scenario. The effects of landslide source parameters on the wave at increasing scales were then investigated.
In order to make use of the findings regarding complex LGW source models, a probabilistic sensitivity analysis on the full range of source parameters and their effect on the generated wave was performed using the SPH simulator. This showed that the geometric landslide parameters (such as volume and submergence depth) contributed more to uncertainty in the resulting wave characteristics near the source than the rheological parameters. By coupling different wave propagation models to the results from the near-field SPH simulator, it was revealed that the choice of mathematical formulation for propagation made a significant difference to which parameters affected the inundation level the most.
These findings have important implications for the design of future LGW modelling studies and which parts of the model workflow should have more computational cost dedicated to them. Near the source the landslide geometry outweighs the complexity of the rheological model in terms of influence on the wave characteristics. During propagation the mathematical formulation chosen can have a large influence on results, so dedicating extra computational cost to this phase would be worthwhile.
Firstly, to model the LGW source as a deformable slide, a smoothed particle hydrodynamics (SPH) simulator was improved and adapted. The simulator was tested using lab scale bench- marks and an idealised full scale LGW scenario. The effects of landslide source parameters on the wave at increasing scales were then investigated.
In order to make use of the findings regarding complex LGW source models, a probabilistic sensitivity analysis on the full range of source parameters and their effect on the generated wave was performed using the SPH simulator. This showed that the geometric landslide parameters (such as volume and submergence depth) contributed more to uncertainty in the resulting wave characteristics near the source than the rheological parameters. By coupling different wave propagation models to the results from the near-field SPH simulator, it was revealed that the choice of mathematical formulation for propagation made a significant difference to which parameters affected the inundation level the most.
These findings have important implications for the design of future LGW modelling studies and which parts of the model workflow should have more computational cost dedicated to them. Near the source the landslide geometry outweighs the complexity of the rheological model in terms of influence on the wave characteristics. During propagation the mathematical formulation chosen can have a large influence on results, so dedicating extra computational cost to this phase would be worthwhile.
Version
Open Access
Date Issued
2020-05
Date Awarded
2020-11
Copyright Statement
Creative Commons Attribution-Non Commercial 4.0 International Licence
License URL
Advisor
Piggott, Matthew
Collins, Gareth
Sponsor
Natural Environment Research Council (Great Britain)/Science and Solutions for a Changing Planet DTP
National Oceanography Centre
Grant Number
NE/L002515/1
Publisher Department
Department of Earth Science and Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)