The computational simulation of seismic waves through a complex Earth model is a major focus of seismology research. These calculations have application across many distance scales from that of exploration geophysics to whole earth seismic structure (see below). The current forefront is solving the elastic wave equation in complex 3-D geometries. The figure opposite shows the results of ray tracing calculations for wavefronts through a complex 2-D structure. A new challenge in geophysics is to perform inversion of complete seismic waveforms for earth structure and source characterization over regional and global scales.
Projects are available in various aspects of theoretical seismology, including methods for wave propagation and inversion. Current interests are in the development to new approaches to wavefield simulation, and multi-phase wavefront tracking in 3-D. Projects are scaled to fit the appropriate degree being undertaken by the student. A background in Physics, mathematics, geophysics, computational science or engineering would be needed to undertake a project in this area.

Contact the supervisor directly for more information.

Today, Earth's oceans are teaming with life, and even deep marine trenches contain enough oxygen to support complex organisms. However, oceans in Earth's distant past were fundamentally different. In the first half of Earth history, 4.5 to 1.8 billion years ago, the world's oceans were almost entirely devoid of oxygen. Astonishingly, for the following one billion years, the state of the oceans remains mysterious. Did the deep oceans become oxygen-rich, in parallel with the Earth's atmosphere, or did they remain anoxic and additionally become sulphidic and toxic? If the world oceans really were anoxic and sulphidic in Earth's middle age, then our understanding of more than 20% of the planet's history would radically change. It would alter our views of global geochemical cycles and may explain why higher forms of life appeared late in Earth history.
In this PhD project, you will elucidate the existence of sulfidic oceans using biomarker molecules extracted from 2.5 to 0.6 billion-years-old sedimentary rocks from Australia, North America and Asia. Biomarkers are the fossil remains of biological molecules. They yield information about the ecology and environment of ancient microbial organisms that lived 1,000 million years before the first animals appeared on Earth. This will be an exciting multidisciplinary project if you have studied geology, chemistry or biology and are interested in evolution and Earth history. It includes geochemical laboratory work and field studies at locations in the world where the oldest biomarkers may be discovered.

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A new approach for the internally consistent modelling of the equation-of state and elastic properties of minerals under the extreme pressure-temperature conditions promises to revolutionise the interpretation of seismological models for the Earth’s interior. The new method has recently been bench-tested on a diverse range of experimental data for magnesium oxide (Kennett & Jackson, Phys. Earth. Planet. Interiors, 2009). Now, there is an opportunity for the involvement of a Ph. B. / Honours/ M. Sc. student in the systematic application of this approach to experimental data, including local measurements of the pressure and temperature dependence of elastic wave speeds, for the upper-mantle mineral olivine and its high-pressure polymorphs wadsleyite and ringwoodite.