The project involves study of the faulting within subduction zone forearcs and associated fluids using seismic reflection and other datasets. Slip on the subduction plate-bounding fault is known to generate large magnitude earthquakes and tsunami, but also produces internal deformation through slip on many faults within the forearc, but these have not previously been systematically studied. The main aims are to understand how these different fault systems develop, how strain is distributed through a forearc, and the role faulting plays in controlling fluid flow within such systems. Gas hydrates and mud diapirism are common at many of these margins and the interaction between faulting and fluid trapping and fluid flow in these environments will be explored. Improved understanding of the development of thrust faults, and other fault types, will provide important data on how faulting affects the potential for fluid storage, including CO2 storage for decarbonisation and trapping of hydrocarbon resources. This project is also relevant to our improved understanding of geohazards in terms of how fluids affect fault slip, generating earthquakes and tsunami, and marine slope failure, which can impact seafloor infrastructure. Example subduction zones to be used in the project are Sumatra, the Makran and Cascadia.
Specific methodologies will include:
1) Interpretation of marine geophysical data (primarily seismic reflection data) and ocean drilling program borehole data (logs and/or cores) for fault location, type, geometry, properties, distribution and slip history;
2) Mapping of the architecture and strain distribution within fault networks and across a forearc;
3) Examination of the seismic properties of fault zones coupled with available seafloor or drilling data to assess evidence for increased pore fluid pressure and fluid flow along faults;
4) Interpretation of the presence and distribution of gas hydrates, of seafloor fluid venting and of mud volcanism;
5) Relating fault properties to fault type, activity, displacement and position within the forearc;
6) Analysing the relationship between faulting and the trapping and flow of fluids within the forearc as a whole; and
7) Comparing results from different margins in order to assess what controls forearc deformation processes and its relationship with movement of fluids in these environments.
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the School of Ocean and Earth Science, within the Geology and Geophysics Research Group. Specific training will include:
· Support from staff within the Geology and Geophysics group who have considerable national and international expertise in subduction zone and natural hazards research;
· Development of skills in geophysical and geological data interpretation, fault analysis and industry-relevant tasks;
· Training in the manipulation and interpretation of seismic reflection, bathymetric and borehole log data for fault, fluid and hydrate interpretation;
· Training in software usage through formal sessions; and
· The opportunity to collaborate with international scientists collaborating with SOES staff on subduction zone research at formal and informal meetings.
This set of training aims is supported by the exceptional computer facilities with state-of-the-art software and hardware for the display, analysis and interpretation of these types of data available to the Geology and Geophysics research group. Members of the group also have access to datasets from many different subduction margins, including Sumatra, Makran, Cascadia, Japan.
Please see https://inspire-dtp.ac.uk/how-apply for details.
Smith, G., McNeill, L.C., Henstock, T.J., Spiess, V., Aranaiz, D., 2014, Fluid generation and distribution in the highest sediment input accretionary margin, the Makran: EPSL, 403, 131-143.
Barnes, P.M., Lamarche, G., Bialas, J., Henrys, S., Pecher, I., Netzeband, G.L., Greinert, J., Mountjoy, J.J., Pedley, K., and Crutchley, G., 2010, Tectonic and geological framework for gas hydrates and cold seeps on the Hikurangi subduction margin, New Zealand: Marine Geology, v. 272, p. 26–48, doi:10.1016/j.margeo.2009.03.012.