Applications are invited for a self-funded, 3 year full time PhD, to commence in October 2019 or February 2020.
The PhD will be based in the School of Earth and Environmental Sciences and will be supervised by Dr. Philip Benson, Dr. Gianluca Tozzi and Dr. Luca De Siena.
The work on this project will involve:
- Conducting simulations of rock deformation (failure) using high force triaxial cells focusing on volcanic rocks (basalt and andesite).
- Using new calibrated micro-seismicity sensors and methods to qualitatively track the source of the earthquakes in space and time.
- Apply these new data to two models, to better understand the role of liquids and attenuation (energy scattering) in the volcano.
Seismic data is by far the most useful signal for volcanic hazard, exemplified by its use for forecasting volcanic eruptions and monitoring aftershock sequences. This project aims to generate a new geophysical (rock-physics) image as a quantified metric at elevated but modest temperatures. The aim of this project is to take existing laboratory data and to calculate likely source mechanisms for two key types of seismicity: Volcano-Tectonic (brittle fracture) and Low-Frequency (primarily driven by rapid fluid flow), as a function of stress and pore fluid decompression / stress, and backed up with physical data using X-Ray Computed Tomography (XCT). Two models will be applied to the data: the crack resonance models of Kumagai and Chouet (2001) and that of Neuberg (Thomas & Neuberg 2013). In both cases, it is postulated that the initial fracturing of country rock provides energy (as a VT event) that subsequently gets trapped by cracks and/or the conduit. The resonance of the cracks/conduits generate resonance that is manifested at LF energy. The project will used the directly measured geometry of the crack and conduit network, as measured via AE and XCT, and link it to the measured energy from the suite of calibrated AE sensors. To test the Kumagai and Chouet model, the known parameters of fluid and rock densities and modulus will be used to calculate a complex frequency via the crack aspect ratios that generate that event, and, in turn, used to calculate a far field seismic signature. This data will then be compared to the calibrated AE to test this limit of the model, to test sensitivity to different parameters, and to forward model the likely cracks based on AE alone. The second model (Neuberg) focuses on the trigger mechanisms itself, and specifically considers a constriction or ‘bottleneck’ on the conduit as a trigger site. This has also been verified in laboratory data in previous work (Benson et al. 2008). By combining new calibrated AE signals with these model outputs, the aim of the project is to better understand the role of fluids in generating volcano seismicity across a range of simulated pressure (depth) conditions.
General admissions criteria
You’ll need a good first degree in an applied science discipline from an internationally recognized university (minimum upper second class or equivalent, depending on your chosen course); an additional Master’s degree in a related area will be an advantage. In exceptional cases, we may consider equivalent professional experience and/or qualifications. English language proficiency at a minimum of IELTS band 6.5 with no component score below 6.0.
Specific candidate requirements
• Hold or expect to hold an good first degree (2:1 or higher) and/or a MSc. in Earth Sciences, Geology/Geophysics or a cognate discipline;
• Have a good working knowledge of numerical software such as excel and be familiar with basic numerical programming methods such as MatLab and Python;
• Have good social and team working skills.
• A working background in laboratory rock mechanics testing – or practical mechanical/electronic engineering skills – are beneficial but not strictly required as training will be provided.
How to Apply
We’d strongly encourage you to contact Dr. Philip Benson ([email protected]
) to discuss your interest before you apply, quoting the project code below.
When you are ready to apply, you can use our online application form and select ‘Geography, Earth and Environmental Sciences’ as the subject area. Make sure you submit a personal statement, proof of your degrees and grades, details of two referees, proof of your English language proficiency and an up-to-date CV. Our ‘How to Apply’ page offers further guidance on the PhD application process.
When applying please quote project code: SEES4941019