In this project the student will make new geodetic observations of transient behaviour of faults in the continents on a variety of temporal and spatial scales. They will use these observations in conjunction with seismicity data and long-term geological observations to test models of fault behaviour.
As the quality of satellite geodetic observations of surface deformation from Global Navigation Satellite Systems (GNSS) and Satellite Radar Interferometry (InSAR) have improved it has been increasingly clear that fault behaviour is not steady-state in time. On short time scales, slow earthquakes, often associated with seismic tremor, have been observed at numerous subduction zones around the world (Bürgmann, 2018), and some creeping segments of strike-slip faults in the continents have also been shown to slip episodically (Rousset et al., 2016) [Figure 1]. Significant changes in deformation rate have been observed on a decadal scale prior to major earthquakes (Mavrommatis et al., 2014). Following earthquakes, postseismic transient afterslip can last for up to a century (Ingleby and Wright, 2017). And on a longer time scale, faults have been observed to change their rates of slip over millennia (Cowie et al., 2017).
The student in this project will use the wealth of geodetic data from Sentinel-1 InSAR, processed by COMET scientists in Leeds, alongside archive data from satellites including ERS and Envisat, and any available GNSS (GPS) data, to investigate how widespread transient behaviour is on faults. They will combine the geodetic data with information from seismicity and quaternary slip rates to understand how deformation rates vary over different timescales. They will use the results to build and test models of the earthquake deformation cycle.
Although the student will lead the overall development of the project, we expect it to include the following elements:
- An assessment of the extent of fault creep on the major faults of the Alpine-Himalayan Belt using data from Sentinel-1.
- Detailed case studies of the temporal behaviour of strain at one or two locations in the Alpine-Himalayan belt, including the integration of seismicity and GNSS (GPS) data.
- The use of long-term slip rate data derived from quaternary dating to assess longer-term slip rate changes.
- The development of numerical models to explain the observations.
The student will be supported by the supervisory team whose expertise covers all aspects of the project. We anticipate there will be opportunity for fieldwork in Italy or Turkey to assist with cosmogenic dating work
Geodetic data are increasingly being used to inform seismic hazard assessments by organisations like the Global Earthquake Model (Wright, 2016). But in order to use the data reliably, we need to understand whether the rates of deformation are steady in time. COMET is building a partnership with the Global Earthquake Model and we anticipate the results from this project in the long term having a major influence on the development of seismic hazard assessments.
The project would suit a numerate student with a background in earth sciences, geology, or geophysics who is enthusiastic about problem solving and the use of satellite geodesy data. The student will be provided with training in state-of-the-art geodetic methods and will have the opportunity to participate in field campaigns. The student will be part of the UK Natural Environmental Research Council’s Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET) and will be expected to interact with COMET students with different skills and backgrounds from across the UK.
In addition, the student will have access to a broad spectrum of training workshops offered in house e.g. image analysis, presentation skills, through to ‘managing your degree’ and ‘preparing for your viva’ (http://www.emeskillstraining.leeds.ac.uk/).
References / Further Reading
BÜRGMANN, R. 2018. The geophysics, geology and mechanics of slow fault slip. Earth and Planetary Science Letters, 495, 112-134.
COWIE, P. A., PHILLIPS, R. J., ROBERTS, G. P., MCCAFFREY, K., ZIJERVELD, L. J. J., GREGORY, L. C., FAURE WALKER, J., WEDMORE, L. N. J., DUNAI, T. J., BINNIE, S. A., FREEMAN, S. P. H. T., WILCKEN, K., SHANKS, R. P., HUISMANS, R. S., PAPANIKOLAOU, I., MICHETTI, A. M. & WILKINSON, M. 2017. Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults. Scientific Reports, 7, 44858.
HUSSAIN, E., HOOPER, A., WRIGHT, T. J., WALTERS, R. J. & BEKAERT, D. P. 2016. Interseismic strain accumulation across the central North Anatolian Fault from iteratively unwrapped InSAR measurements. Journal of Geophysical Research: Solid Earth, 121, 9000-9019.
INGLEBY, T. & WRIGHT, T. 2017. Omori‐like decay of postseismic velocities following continental earthquakes. Geophysical Research Letters, 44, 3119-3130.
MAVROMMATIS, A. P., SEGALL, P. & JOHNSON, K. M. 2014. A decadal‐scale deformation transient prior to the 2011 Mw 9.0 Tohoku‐oki earthquake. Geophysical Research Letters, 41, 4486-4494.
ROUSSET, B., JOLIVET, R., SIMONS, M., LASSERRE, C., RIEL, B., MILILLO, P., ÇAKIR, Z. & RENARD, F. 2016. An aseismic slip transient on the North Anatolian Fault. Geophysical Research Letters, 43, 3254-3262.
WRIGHT, T. J. 2016. The earthquake deformation cycle. Astronomy & Geophysics, 57, 4.20-4.26.