Numerical modelling of volcano stability with application to caldera collapse
Caldera collapse is a catastrophic event often associated with a large volcanic eruption: the drainage of large volumes of magma from subsurface reservoirs leads to the collapse of the volcanic edifice, resulting in large circular depressions at the surface.
Good examples of caldera collapse are Santorini and the myth of Atlantic, the AD 79 Mount Vesuvius eruption and the destruction of Pompei, and the gigantic 1991 eruption of Pinatubo, Philippines. Even if numerous volcanic eruptions occurred during the XX century, only a few (5-6) lead to caldera collapse, such that direct observations of caldera collapse are lacking. Consequently, the physical conditions of (1) the onset of caldera collapse and (2) the structural development of collapse calderas are very poorly understood.
The aims of this MSc project are to explore the physical parameters that control the onset of caldera collapse and quantify the associated subsurface structures.
The project is based on limit analysis numerical modelling, which is a standard engineering tool commonly applied to assess the stability of slopes, rock masses and buildings. The principal of limit analysis is to predict approximate values of loads that bring a brittle solid to an imminent state of failure.
The numerical modelling will be performed using the graphic-interface OptumG2 modelling package; this implies that no advanced coding is necessary for the success of the proposed project. The implementation of OptumG2 is as follows: the user defines the geometry of a magma reservoir at a given depth within the brittle crust and the mechanical properties of the crust. The modelling package will calculate the critical pressure in the magma reservoir that leads to a collapse of the overlying crust, and it will also calculate the geometry of the expected failure structures.
The aim of the project is to explore the geometric and mechanical conditions of caldera onset.
The project will be organized according to the following steps:
- Initiation to the modelling technique during the GEO4151 course: “Earthquake and volcanic processes”;
- Running selected series of numerical models;
- Data analysis;
- A physical interpretation of the models, and integration with the numerical models of the laboratory MSc project (if implemented).
The learning outcomes are the following:
- Modelling strategy;
- Quantitative physical analysis;
- Physics of rock stability, which is applicable to other geological systems (landslides, avalanches, geotechnics);
- Multi-disciplinary work.
To implement this project, it is recommended to have:
- Basic knowledge in programming skills, in order to analyze the results produced in the numerical models. Note that the proposed numerical model runs with a good graphic interface, therefore no advanced programming is required to run the models.
- Basic knowledge in brittle rock mechanics.
The skills to be acquired during this MSc projects are highly relevant both for geotechnical and consulting careers, as well as academic careers.