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Postgraduate opportunities for geophysics research

We are eager to take on new postgraduate students to work and study in the seismology group at the University of Otago. New Zealand is a fantastic place to study geology in general and geophysics in particular. Please feel free to contact Assoc Prof Andrew Gorman with any specific questions. For general information on postgrad studies at the University of Otago, please see application information webpages. Australian students should note that they are eligible for domestic fees and many domestic scholarships. Citizens/residents of most other countries must pay foreign fees. As of 2006, there are no longer any foreign fees for PhD study in New Zealand.

Successful postgraduate studies require the combination of three elements:

  1. a good work/study environment
  2. a good relationship with your research supervisor
    and most importantly -
  3. a research topic that you are enthusiastic about

We encourage all postgrads to develop their own research proposal prior to starting their studies. To get you thinking, here are some suggestions.

Possible research topics include the following

Seismic imaging of New Zealand's offshore basins

An extensive data set of marine seismic reflection data from several offshore sedimentary basins is publicly available for academic research in New Zealand. Numerous research projects are possible that could make use of these data to address significant geological problems (e.g., tectonic history, structural evolution, sedimentological environments, and fluid migration patterns). This project could link in well with multidisciplinary studies as part of the department's Southern Basins Research Initiative.

Gas hydrate characterisation on New Zealand's margins

The public database of New Zealand marine seismic reflection data has been used to characterise gas hydrate occurrences on the Fiordland and Hikurangi continental margins. However, there are many questions yet to be answered about the variability of hydrate distributions and their effect on the sediments that host them. In particular, hydrates have not been definitively identified along the passive margins of New Zealand - even though several of these regions contain hydrocarbon systems. Possible research topics may make use of the University's research vessel, RV Polaris II, to examine fluid escape structures on the continental slope that may be related to methane escape.

Seismic sub-bottom imaging and seafloor bathymetry: data acquisition , processing and interpretation

The University of Otago’s research vessel, Polaris II, is equipped with a Teledyne-Benthos tow fish that comprises a bathymetric side-scanning sonar and a CHIRP sub-bottom profiler. We also have run a Ferranti seismic boomer sub-bottom profiler for 20 years. An extensive data set of seismic boomer seismic profiles from coastal waters around the South Island of New Zealand has been acquired (by RV Munida until 2006 and now RV Polaris II). Postgraduate research could involve the synthesis of existing data with new data sets (which you could acquire yourself) to gain a regional understanding of near shore sedimentary deposits and their relation to underlying geology. Alternatively, sub-bottom imaging could be used to examine shallow structures or fluid migration pathways.

Using seismic oceanography to characterise the variability of ocean the Southland Current east of the South Islandwater masses

Our group is currently working on cutting-edge seismic imaging of ocean water masses using seismic oceanographic techniques. Coast-parallel currents and their related features, e.g., the Southland Current and Subtropical Front, often play a critical role in regional and global climate and can affect fishery stability and productivity and marine industries. Studies at several places around the world have indicated that seismic oceanographic techniques can be used to investigate the spatial and temporal extent of these currents. New seismic oceanography projects might include using publicly-available databases of seismic reflection lines collected for the petroleum industry to examine particular features of the water column.

Lithospheric characterisations using exisiting seismic data sets

Refraction and wide-angle reflection (R/WAR) data are acquired to examine lithospheric structure. In New Zealand, an excellent R/WAR data set was collected in 1996 across the South Island. The South Island Geophysical Transect (SIGHT) data have provided new insight into the structure of the crust and upper mantle in the vicinity of the Pacific - Australian plate boundary through New Zealand. Further analysis of the data is needed to examine the variable nature of deep lithosphic layers across this boundary. For example, lower crustal and Moho reflections in the data have inconsistent seismic signatures; it would be desirable to gain insight into the reason for this variability. A research project in this field would likely involve the use of finite-difference modelling of the seismic wavefield. Comparitive studies are possible with, for example, similar Lithoprobe data sets acquired in Canada.

Shallow crustal seismic acquisition, processing and interpretation

Opportunities abound for the use of the department's 48-channel seismograph for shallow crustal investigations of New Zealand geology. Over the last few years, we have used this equipment for several research projects. These include imaging studies of: 1. the Ostler Fault zone in Mackenzie County, 2. the seafloor geology beneath the McMurdo Ice Shelf in Antarctica, 3. the Oreti River aquifer in Southland, 4. the Foulden Hills Maar in eastern Otago, 5. the onshore Canterbury Basin near Cave in South Canterbury, 6. Macraes goldfield in eastern Otago, 7. the Alpine Fault at Haast and 8. the Alpine Fault at Whataroa. Other proposals for seismic acquisition, processing and interpretation projects are welcome!

Numerical modelling with seismic applications

Genetic algorithm methods have been posed as a technique for optimising lithological model development based on input seismic data. A potential research project could involve the application of this method to high-resolution seismic wavefield data in such areas as gas-hydrate provinces (see above). Such a project would involve the modification and development of computer software used for the seismic inversion.

    

Andrew Gorman