The Stress Evolution of Earthquake Sequences: Hunting for Possible Pre-cursors

Apply now. ARIES PhD project opportunities October 2021

Supervisors

Dr Zoe Mildon (School of Geography, Earth and Environmental Sciences, University of Plymouth)

Dr Jessica Johnson (School of Environmental Sciences, University of East Anglia)

Dr Irene Manzella (School of Geography, Earth and Environmental Sciences, University of Plymouth)

Professor Mark Anderson (School of Geography, Earth and Environmental Sciences, University of Plymouth)

Supervisors

Dr Zoe Mildon (School of Geography, Earth and Environmental Sciences, University of Plymouth)

Dr Jessica Johnson (School of Environmental Sciences, University of East Anglia)

Dr Irene Manzella (School of Geography, Earth and Environmental Sciences, University of Plymouth)

Professor Mark Anderson (School of Geography, Earth and Environmental Sciences, University of Plymouth)

Project background

This project will investigate how tectonic stress in a fault system varies over time and whether it affects the location, timing and magnitude of a sequence of damaging earthquakes. This will have implications for understanding why earthquake sequences happen and how the hazard and risk varies.

Earthquake sequences, where several damaging events occur over a few weeks in the same area, are difficult to incorporate into seismic hazard calculations because the driving factors behind why they happen are poorly understood. For the 2016 central Italy earthquake sequence, it’s been suggested that the state of stress before the beginning of the earthquake sequence may affect the timing and location of large (M>6.0) earthquakes (1). Measuring the in-situ stress state of the crust is challenging experimentally, but prior studies have shown this is possible by studying localised microseismicity and seismic anisotropy (2). In addition, features of the microseismicity may change throughout a sequence, such as the magnitude, temporal/spatial clustering or the b-value (describes the ratio of large to small earthquakes). These changes are poorly understood but could be used to quantify potential pre-cursors for large and damaging events, and ultimately understand why earthquake sequence occur.

Research methodology

The candidate will learn to use a variety of computer-based modelling and analysis, including waveform picking, analysing crustal anisotropy, modelling stress transfer, and applying machine learning to geological data. The candidate will spend time at UEA throughout the PhD to learn from the co-supervisor.

Training

The candidate will learn to utilise, develop and write code to locate earthquakes, calculate seismic anisotropy and model stress evolution. Machine learning will be utilised which has applications to several different fields in academia and industry. All training will be provided by the supervisory team.

Person specification

We are looking for applicants with a degree in geology, geophysics or physics and an interest in understanding earthquake hazard. The candidate should be numerically literate, experience of using Matlab or Python and familiarity with Linux is desirable but not essential.

References

  • 1. Mildon, Z. K., Roberts, G. P., Faure Walker, J. P., & Iezzi, F. (2017). Coulomb stress transfer and fault interaction over millennia on non-planar active normal faults: the M w 6.5–5.0 seismic sequence of 2016–2017, central Italy. Geophysical Journal International, 210(2), 1206-1218.
  • 2. Johnson, J. H., Savage, M. K., & Townend, J. (2011). Distinguishing between stress‐induced and structural anisotropy at Mount Ruapehu Volcano, New Zealand. Journal of Geophysical Research: Solid Earth, 116(B12).
  • 3. Mildon, Z. K., Toda, S., Faure Walker, J. P., & Roberts, G. P. (2016). Evaluating models of Coulomb stress transfer: Is variable fault geometry important?. Geophysical Research Letters, 43(24), 12-407. 

Key information

  • This project has been shortlisted for funding by the ARIES NERC DTP and will start on 1 October 2021. The closing date for applications is 23:59 on 12 January 2021.
  • Successful candidates who meet UKRI’s eligibility criteria will be awarded a NERC studentship, which covers fees, stipend (£15,285 p.a. for 2020-21) and research funding. For the first time in 2021/22 international applicants (EU and non-EU) will be eligible for fully-funded UKRI studentships. Please note ARIES funding does not cover visa costs (including immigration health surcharge) or other additional costs associated with relocation to the UK.
  • ARIES students benefit from bespoke graduate training and ARIES provides £2,500 to every student for access to external training, travel and conferences. Excellent applicants from quantitative disciplines with limited experience in environmental sciences may be considered for an additional 3-month stipend to take advanced-level courses in the subject area.
  • ARIES is committed to equality, diversity, widening participation and inclusion in all areas of its operation. We encourage enquiries and applications from all sections of the community regardless of gender, ethnicity, disability, age, sexual orientation and transgender status. Academic qualifications are considered alongside significant relevant non-academic experience.
  • All ARIES studentships may be undertaken on a part-time or full-time basis, visa requirements notwithstanding
  • For further information, please contact the supervisor.