Geophysics Research Themes

Research in the group is currently concentrated in two primary areas, earthquake physics and fluid flow in complex media. A common theme underlying all our work is that recognition that heterogeneity and complexity have a first order effect on natural processes.

Earthquake physics

An important area of our research is stress interaction and earthquake triggering; in particular the potential for using co-seismic stress changes to constrain the likely locations of future large earthquakes. This work has been funded by NERC (1999, 2000, 2003, and 2005) and the European Commission through FP5 and FP6 (2000 and 2005). The most dramatic example of the our publications on this topic was the paper in Nature that warned of the likelihood of a further large earthquake off the coast of Sumatra; the article was published 11 days before the M=8.7 Nias earthquake of 28 March 2005. Related work has been published in Journal of Geophysical Research, Geophysical Journal International, Earth and Planetary Science Letters, and Nature. Additionally, Sandy Steacy co-edited a Special Section of JGR on stress triggering and was lead author of a review paper on the subject.

As a natural follow-on from the Sumatra studies, we developed an interest in modelling the next likely tsunami in the Indian Ocean. In a NERC funded (2005) collaboration with Caltech and INGV-Rome the team has produced novel new results on the controls on tsunami waveforms and timing in the near field as well as on the importance of earthquake complexity on tsunami wave heights. John McCloskey has given several invited talks on this work to both scientists and end-users, the latter in Oxford and Malaysia.

We have also developed a sophisticated seismic simulation model to investigate earthquake triggering. Parallelization of the model was funded by EPSRC (2001) and it is presently being used in NERC funded (2007) research to investigate the assumptions underlying the rate-state approach to calculating stress based earthquake probabilities.

Fluid flow in complex media

Fluid flow research has focused on the importance of complexity in the validity of up-scaling from the laboratory to the field and the need to develop tracer technology to measure complexity at the scale of interest. In response to the lack of high resolution empirical data for the validation of numerical models of fluid flow, we developed an experimental imaging system to measure velocity fields in complex synthetic rock and fracture models. This work was supported by the NERC micro-to-macro thematic project (2000) and it uncovered significant problems with the representation of viscosity in the widely used modified Lattice-Boltzman scheme and with upscaling in fractal media. The experimental design was published in Machine Vision and Applications as well as IEEE, and the results in the Journal of the Geological Society.

This work, and the consequent recognition that complex systems must be studied at the scale of interest, has led to the Group pursuing the development of new tracer technologies that allow the creation of an almost infinite range of unique tracers, are environmentally benign, and have very low detection limits. This research was funded by InvestNI (2004) under their Proof of Concept scheme and NERC (2005) and is the subject of a current patent application.