The effect of fault network geometry on the behaviour of normal faults using earthquake modelling and field observations
Lead Supervisor: Dr Constanza Rodriguez Piceda
Location: University of Plymouth, School of Geography, Earth and Environmental Sciences
Duration: 6 weeks
Suitable undergraduate degrees: Geology or Geophysics
Project background
Motivation
Commonly, seismic hazard assessment uses fieldwork measurements of fault slip rate and earthquake records (Gerstenberger et al., 2020). However, this is particularly challenging in active extending regions, such as the Italian Apennines, because these normal faults tend to exhibit low seismicity rates and magnitudes lower than Mw 7. Also, we don’t fully understand how the fault network geometry affects earthquake behaviour over many seismic cycles.
Therefore, to better constrain the seismic hazard, it is critical to understand the underlying mechanisms behind earthquake clustering, synchronization between faults and the generation of complex earthquake sequences. In this project, computer-based earthquake cycle modelling will be used to explore how the fault network geometry (spatial arrangement and separation) affects the earthquake behaviour of two normal faults. From these models, important parameters for seismic hazard assessment, such as the earthquake recurrence interval and coefficient of variation (Visini and Pace, 2014), will be extracted and analysed. Additionally, optional fieldwork to the Italian Apennines will be used to gain insights into the natural variations in fault geometry.
This project will combine scientific-computational methods and field observations to investigate the role of the fault network geometry in the seismic cycle of normal faults and their slip rate behaviour. The project will contribute to current understanding on fault behaviour and its impact on seismic hazard assessment.
Aims and objectives
The overall aim of the project is to understand how fault system geometry affects the earthquake behaviour of normal faults. This aim will be achieved through the following objectives
- Undertake earthquake cycle modelling for two en-echelon faults with variable across- and along-strike spacings, to determine earthquake cycle parameters including magnitude, rupture extent and recurrence times.
- Analyse the outputs of the modelling to understand how fault spacing affects the earthquake cycle parameters.
- Study natural examples of normal fault scarps in the Italian Apennines to understand the natural variability of fault geometry.
Workplan and skills development
The student will use a combination of computer-based modelling and fieldwork to achieve the aim of the project.
Computer-based modelling will use QDYN (Luo et al. 2017) to simulate numerous earthquake cycles on two planar normal faults, with variable across- and along-strike distances. The outputs of the modelling (e.g. earthquake recurrence time) will be analysed to determine how the fault spacing controls earthquake behaviour in the modelled system. Training will be provided to use QDYN, though coding experience (e.g. Python and/or MATLAB) would be desirable.
Fieldwork in the Apennines will collect information on throw profiles and slip vectors along the scarps of normal faults to characterize the geometry and possible subsurface connectivity of faults. If the student is unable to do fieldwork, then there is a wealth of existing data that they could work with.
The student will have the opportunity to present their work informally to colleagues in the university, and the option to write a blog article for the Geodynamics Division of the European Geoscience Union.
References:
(Gerstenberger et al., 2020) Rev. Geophys., Visini and Pace, 2014, BSSA.