How do complex fault geometries influence earthquake cycle deformation?

About the Project

The School of Earth, Environment, and Sustainability at the University of Leeds invites applications from prospective postgraduate researchers who wish to commence study for a PhD in the academic year 2026/27. This opportunity is open to UK applicants and covers UK fees plus a maintenance allowance matching current UKRI rates (£21,805 in 2026/27).

This exciting project aims to understand how complicated fault geometries influence earthquake style and recurrence. You will combine field work, lab analyses, and seismology to investigate fault slip patterns on multiple scales in time and space.

Heterogeneities in fault system geometries may strongly influence earthquake nucleation and recurrence (Cowie et al., 2012; Dieterich and Richards-Dinger, 2010; Walters et al., 2018). In particular, normal faults display complex geometries due to the mechanisms by which they evolve and grow, and the relationship between repeated faulting and the growth of topography in the footwall (Ciftci and Bozkurt, 2007; DuRoss et al., 2019). Fault geometry complexities such as segmentation, relays, and branches can act as persistent barriers to rupture, but might also invoke heterogeneities in stress and strength that could influence the size and frequency distributions of earthquake rupture (Goebel et al., 2015). In this project you will characterise fault behaviour across different scales in time and space to better quantify how complex geometries may influence patterns of earthquake recurrence.

Full description

Faults in the V-shaped Dinar-Baklan basin in western Turkey intersect at a perpendicular angle at the fault terminations. There are three main faults accommodating extension across the region, including the Dinar fault that ruptured in an Ms 6.1 eathquake on the 1 October, 1995 (Altunel et al., 1999; Eyidogan and Barka, 1996). Localities have been identified to collect samples to measure the Quaternary fault slip rate, and how it varies through time, on each fault using cosmogenic isotope analyses. Cosmogenic isotopes are a Quaternary dating technique that quantifies how earthquakes have displaced the ground surface over multiple earthquake cycles and thousands of years (Goodall et al., 2021; Schlagenhauf et al., 2010). Results from these analyses will illuminate how the fault slip rate has varied over time, and whether these three faults have similar patterns of displacement.

Deformation across western Turkey is accommodated on a complicated network of large normal faults with variable orientations (Bozkurt, 2003; Bozkurt and Sozbilir, 2004; Uzel, 2016). Rapid extension is distributed across the large network of normal faults, but exactly how each fault contributes, and whether there are major unknown faults that also may be important, is still unknown (e.g. Nissen et al., 2022). This project will aim to determine the precise geometry of the Dinar-Baklan basin faults at depth using geological mapping, cross sections, and seismology. The surface expression of the faults will also be mapped in detail using Terrestrial Laser Scanning (TLS), UAV – RS, and field mapping to characterise which aspect of geometry are likely to be important at depth. Further seismological observations covering western Turkey will aim to quantify characteristics of faulting (b-values, empirical density distributions), which will help to understand how regional deformation varies in space and time.

Ultimately, regional earthquake statistics can be used to conduct physics-based earthquake models that can be incorporated into statistically based earthquake hazard models (Shaw et al., 2018). This project aims to gain a better understanding of how complex faulting may influence the pattern of earthquakes across western Turkey, and has the potential for significant scientific and human impact.

Objectives

1. Determine detailed fault slip rates on three faults in western Turkey using cosmogenic isotope analyses on bedrock fault scarps (Cowie et al., 2017; Goodall et al., 2021). You will conduct fieldwork to collect samples from sites identified previously and conduct detailed field-based surveys of the sites (e.g. using Terrestrial Laser Scanning, TL; Bubeck et al., 2015). You will process the samples in the lab, analyse the results, and model the data using Bayesian MCMC methods to determine time-variable fault slip rates for each fault.
2. Investigate the structure of the Dinar – Baklan basin at depth using field based geological mapping, cross sections, and available seismological data. Combined with fault slip rate data, you will aim to better understand how cross-cutting basins evolve and interact at depth. You will investigate whether there are major barriers to rupture of these complex faults, and there is scope to conduct rupture modelling to determine how rupture scenarios might evolve over multiple earthquake cycles on intersecting faults.
3. Investigate the seismological characteristics of normal faults across western Turkey to quantify earthquake statistics for the complex network of faults that span this region (Dieterich and Richards-Dinger, 2010). Depending on your interests, you may further investigate fault properties by investigating paleostress indicators and fault surface roughness.

Fit to NERC science

This project directly addresses NERCs aim to tackle challenges faced by the world in the fields of hazards and solid earth science. NERC has a priority to increase the understanding of environmental hazards to manage vulnerability, risk, response and recovery – and this project aims to better understand the fundamental processes that affect how and when earthquakes occur. We will be working in western Turkey, which hosts many earthquakes and where there are significant populations exposed directly to this hazard. Our research will not only improve our understanding of fundamental processes of earthquakes in general, but also specifically on the targeted faults in western Turkey.

Logistics

You will be based in the School of Earth, Environment, and Sustainability at the University of Leeds. You will work alongside scientists and students in the Institute of Geophysics and Tectonics. You will also be part of the UK-wide network COMET, the Centre for the observation and modelling of earthquakes, volcanoes, and tectonics.

Funding Notes

We are offering a fully funded scholarship to study the project ‘How do complex fault geometries influence earthquake cycle deformation?’, at the school of Earth, Environment, and Sustainability, University of Leeds for one UK status candidate. The funding covers UK tuition fees as well as a UKRI matched maintenance stipend (currently £21,805 in 2026/27) per year, for three and a half years, subject to satisfactory progress.

Applicants must be eligible to pay fees at the Home (UK) rate.

If you are unsure whether you are eligible for UK fees/funding, please see our fee assessment page.