Geophysics, Geodynamics and Tectonics.
Robert White is accepting applications for PhD students.
Robert White is available for consultancy.
Rifting and Volcanism
Magmatism associated with rifting is one of the most important factors in shaping the crust: two-thirds of the earth's crust forms at mid-ocean spreading centres, and many of earth's most spectacular features, including flood basalts and volcanoes, result from interaction between rifting and mantle melting. Relatively small changes in mantle temperature have a profound effect on the volume and composition of melts produced from that mantle. Understanding these processes is important not only academically, but also for wider social reasons because of the hazards of volcanic eruptions, their impact on global climate change, and their importance in the development of sedimentary basins and continental margins. Much of our understanding of these processes comes from probing the subsurface using seismic methods. My research group acquires state-of-the- art seismic data from both controlled sources and earthquakes, on land and at sea, and at all scales from metre-size observations in boreholes to hundred-kilometre scale transects of rifted continental margins. We seek to apply innovative data processing and modelling methods to maximise the geological constraints that can be inferred from these observations.
Current Research Projects
- Tomographic imaging of melt bodies under active volcanoes in Iceland and New Zealand using large arrays of broad-band seismometers. We have a particular focus currently on the north Iceland volcanic rift, where we have for the first time mapped small earthquakes at 15–30 km depth beneath the active Askja volcano which we believe are caused by catching melt in the act of intruding along the rift in the normally ductile lower crust.
- Detailed properties of basalts, including their attenuative and anisotropic properties by making detailed vertical seismic profiles, walkaway and refraction studies around boreholes in the Faroe Islands, and combining the seismic results with ground truth from borehole logging and sampling. This also feeds into our development of improved sub-basalt imaging using long (12,000 m) streamers, powerful low-frequency airgun sources, and 4-component ocean bottom seismometer (OBS) recording of wide-angle data.
- Improved understanding of rifted continental margins by combined wide-angle recording with OBS to provide good P-wave and S-wave velocity control with deep penetration seismic reflection data capable of imaging structure within the basalts and in the lower crust and upper mantle. We are currently working on two excellent 300-km long profiles across the North Atlantic volcanic rifted margins which are providing new constraints on the volumes and properties of the extrusive and intrusive melts emplaced at the time of continental breakup.
- Development of improved methods of mapping fluid motions in the subsurface from surface seismic monitoring of hydrofractures in subterranean reservoirs.
- Development of a broader view of the sustainable use of the environment using scientific, social, and ethical insights.