'Investigating the Earthquake Cycle of Normal Faults'
Supervisors: Prof. Andreas Rietbrock
Description: My PhD research mainly involves the use of Interferometric Synthetic Aperture Radar (InSAR) to study crustal deformation associated with the earthquake cycle of normal faults. In addition to studying the mechanics of continental normal faulting earthquakes on the Tibetan Plateau, I am working on intra-slab normal faulting earthquakes in Chile, to constrain subduction zone rheology. The main objectives of my research can be summarized into the four following aspects: 1) to use geodetic data and numerical models to better constrain normal faulting earthquake ruptures, 2) to build up local lithospheric strength profiles based on geodetic results, 3) to investigate fault interaction based on Coulomb stress changes, 4) to assess the influence of post-seismic viscoelastic relaxation following deep intra-slab normal faulting earthquakes on the subduction zone earthquake cycle - Email Lidong
Supervisors: Andreas Rietbrock & Ben Edwards
Description: - Email Minxuan
'The Role of Lithosphere Hyper-Extension in the Formation of Magma-rich Continental Margins from Deep-Seismic Reflection Data'
Supervisors: Prof Nick Kusznir & Prof Andreas Rietbrock
Description: Magma-rich continental margins are poorly understood in comparison to their non-volcanic counterparts due to the presence of magmatic material obscuring the crust. This work will investigate the structural and formation processes of these margins through the use of gravity and joint inversions, as well as subsidence and residual depth analyses which will help reveal information about crustal thickness, lateral variations in basement density and seismic velocity, the distribution of thinned continental basement and the existence or absence of conjugate margin asymmetry. The resulting information will have important implications for plate tectonics and geodynamics as well as deep-water hydrocarbon exploration. - Email Caroline
'Seismic properties and processes along the Subduction plate interface: the February 2010 Mw 8.8 Maule Earthquake, Chile'
Supervisors: Prof Andreas Rietbrock
Description: The seismogenic zone of subduction margins has the potential to generate some of the world’s largest earthquakes, such as the 2004 M9.1 Sumatra and 2011 M9.0 Japan earthquakes. My project is focuses on the 2010 Mw 8.8 Maule, Chile rupture: the sixth largest earthquake ever recorded, and has shed light on some of the controls that govern subduction zone seismic behaviour across the earthquake cycle. We used aftershock seismicity from the Maule earthquake to generate a detailed image of the ruptured fault using seismic tomography. Our 3-D images reveal that a strange structure lies along the fault, which appears to have slowed down the 2010 rupture. It is likely made up of ancient, dense mantle material from over 200 million years ago. Another part of my project has been to image the complexity of the earthquake rupture process. Using 3-D numerical simulations of seismic wave propagation that are calculated on supercomputers, we find that a large earthquake in the Chile subduction zone instantly triggered a shallow rupture in the upper plate. Such shallow ruptures are important for understand the hazard from potentially dangerous tsunami along the Pacific Ring of Fire. - Email Stephen
'Next-Generation Ground Motion Prediction Models for Probabilistic Seismic Hazard Analysis (PSHA)'
Supervisors: Andreas Rietbrock & Ben Edwards
Description: Probabilistic Seismic Hazard Analysis (PSHA) is the current industry standard method for assessing seismic hazard for engineering applications. The probabilistic nature of this method allows consideration of both the aleatory uncertainty and the epistemic uncertainty in the seismic hazard model. Ground motion prediction equations (GMPEs) are a crucial input for PSHA, however, these models suffer from large epistemic uncertainties.
There are disagreements in the seismological community as to which is the best approach. The most commonly used approach is empirical modelling. These models are produced using real data (usually via some form of regression analysis) and information about the source, path and site effects. Using this information models are calibrated to predict ground motion (Peak Ground Acceleration (PGA), Pseudo-Spectral Acceleration etc.) at some offset using variable distance metrics from the earthquake source (epicentral distance [Repi], Joyner-Boore distance (Rjb) etc.). Empirical GMPEs are often statistically dependent as they rely on similar datasets for calibration. It is well known that our current sample space is incomplete and there are large gaps in data particularly for large magnitudes in the near field (>M7; <50km). For this reason, seismologists have turned towards stochastic and deterministic approaches. It is widely accepted that they will pave the way for more complete GMPEs in the future; thus reducing the current epistemic uncertainty. - Email James
'Mantle serpentinization, carbon and life'
Supervisors: Nick Kusznir, George Wolff, John Wheeler and Gianreto Manatschal (University of Strasbourg, France)
Description: Observations at hydrothermal systems in modern ocean settings suggest that methane produced by serpentinization can support methanotrophic bio-systems. An important question is whether such bio-systems are localised or are more pervasive in their association with serpentinized mantle in the subsurface. The aims of this PhD are to search for molecular evidence of methanotrophic bacteria and to understand its distribution within serpentinized exhumed mantle. This could have implications for the global importance of the hidden sub-surface bio-systems, the fate of methane and the carbon cycle. - Email Tsvetomila
Júlia Gómez Romeu
'Geometry & Mechanics of Extensional Faulting During Continental Breakup and Sea-floor Spreading Initiation'
Supervisors: Prof. Nick Kusznir and Gianreto Manatschal
Description: The geometry and mechanics of upper lithosphere extensional faulting during the progression from continental rifting to continental breakup and sea-floor spreading initiation is controversial. The aim of this PhD project is to develop a model of extensional fault geometry and mechanics occurring at rifted continental margins leading to continental breakup and sea-floor spreading initiation. To achieve this, seismic reflection data, earthquake seismology, geological maps and other data will be used. - Email Julia