South Island
Objective Leader: Dr. Simon Cox
This objective aims to quantify regional patterns of deformation, surface faulting and erosion processes, and the crustal structure of South Island. The work will improve seismic and landslide hazard assessment, provides baseline data on natural variability for regional planners and climate-change research, and valuable data for the petroleum industry. We will use seismic, GPS, magneto-telluric, and geological data, integrated using finite-element modelling. Outcomes will be achieved by direct communication of results to applied hazards and resources research programs via publications and conference presentations.
We currently have seven tasks within the objective:
1 Horizontal motions from GPS surveys (leader Dr. John Beavan): Geodetic surveys and inversion modelling to determine where and how surface deformation has occurred in the South Island over the last decade.
2 Vertical motions from GPS surveys (leader Dr. John Beavan): Investigating mountain building processes by collecting continuous GPS data across the Aoraki/Mt Cook region and measuring how fast the mountains are rising.
3 Crustal structure from magneto-telluric surveys (leader Grant Caldwell): Experiments to determine whether high electrical conductivity crust beneath the central Southern Alps occur elsewhere beneath the mountains, and if conductivity (aka fluid flow) varies between earthquakes.
4 Crustal structure from seismic surveys (leader Dr. Stephen Bannister): Geophysical surveys and seismic analysis to investigate the structure and rheology of rocks beneath the central South Island, with a view to estimating their effects on fault rupture and outlining features affecting hydrocarbon potential.
5 The Alpine Fault (leader Dr. Rob Langridge): Collection and integration of data to determine the nature and past motion of the Alpine fault for dissemination to other scientists working earthquake hazard modelling and continental collision processes.
6 Geological studies of South Island faults (leader Dr. Simon Cox): Alpine fault slip accounts for c. 75% of plate motion, with the other 25% Quaternary deformation essentially "missing" from our records. Geological investigations aim to determine slip rates on faults in Marlborough and within the Southern Alps region, in an attempt to define the nature of this "missing" deformation.
7 Numerical modelling of South Island deformation (leader Dr. Susan Ellis): Numerical experiments testing whether or not interseismic surface deformation across the South Island is significantly affected by crustal material properties and structure associated with the Alpine Fault and ductile lower crust.
And our most recent initiative is a plan to drill into the Alpine Fault
Click here to see a full proposal.
DFDP-AF_public_ws_ICDP2008.pdf (820.05 kB)
Selected publications
Okaya, D., Stern, T., Davey, F. 2007. A continental plate boundary: tectonics at South Island, New Zealand. Geophysical Monograph 175. American Geophysical Union. pp. 369.
Beavan, R.J., Reyners, M.E.. 2003. Quake yields tsunami of data. New Zealand Geographic, 66: 6-9.
Beavan, J.; Matheson, D.; Denys, P.; Denham, M.; Herring, T.; Hager, B.; Molnar, P. 2004. A vertical deformation profile across the Southern Alps, New Zealand, from 3.5 years of continuous GPS data. In: Proceedings of Workshop, The State of GPS Vertical Positioning Precision: Separation of Earth Processes by Space Geodesy, Cahiers du Centre Européen de Géodynamique et de Séismologie, Vol. 23, eds. T. van Dam and O. Francis, pp. 111-123, Luxembourg, 2004.
Eberhart-Phillips, D., and Bannister, S., 2002, Three-dimensional crustal structure in the Southern Alps region of New Zealand from inversion of local earthquakes and active source data, Journal of Geophysical Research, 10.1029/2001JB000567.
Gerbault, M., Henrys, S., and Davey, F. 2003. Numerical models of lithospheric deformation forming the Southern Alps of New Zealand, Journal of Geophysical Research 108, 2341, doi:10.1029/2001JB001716, 2003.
Gerbault, M., Davey, F., and Henrys, S., 2002. Three-dimensional lateral crustal thickening in continental oblique collision: an example from the Southern Alps, New Zealand, Geophysical Journal International 150: 770-779.
Little T.A., Cox S.C., Vry J.K., Batt G. in press. Variations in exhumation level and uplift-rate along the oblique-slip Alpine fault, central Southern Alps, New Zealand. Geological Society of America Bulletin.
Long D T, Cox S C, Bannister S, Gerstenberger M C, Okaya D. 2003. Upper crustal structure beneath the eastern Southern Alps and the MacKenzie Basin, New Zealand, derived from seismic reflection data. NZ Journal of Geology & Geophysics 46(1): 21-39.
Nicol, A.; Van Dissen, R.J. 2002 Up-dip partitioning of displacement components on the oblique-slip Clarence Fault, New Zealand. Journal of Structural Geology, 24: 1521-1535.
Reyners, M.E. et al. 2003 The Mw 7.2 Fiordland earthquake of August 21, 2003 : background and preliminary results. Bulletin of the NZ Society for Earthquake Engineering, 36(4): 233-248.
Rhoades, D.A.; Van Dissen, R.J. 2003. Estimates of the time-varying hazard of rupture of the Alpine Fault, New Zealand, allowing for uncertainties. NZ Journal of Geology & Geophysics 46(4): 479-488.
Wannamaker, P.E.; Jiracek, G.R.; Stodt, J.A.; Caldwell, T.G.; Gonzalez, V.M.; McKnight, J.D..; Porter, A.D. 2002. Fluid generation and pathways beneath an active compressional orogen, the New Zealand Southern Alps, inferred from magnetotelluric data. Journal of Geophysical Research107(B6): doi:10.1029/2001JB000186
Follow the links above to individual research project pages.