2017 Msci Geophysics, Imperial College London.
Masters dissertation title: A new methodology for the implementation of full waveform inversion.
Bachelors dissertation title: The Regional Tectonic Analysis of the Juan De Fuca Microplate System using Passive Seismics.
Internal: Dr Adam Booth and Professor Graham Stuart
External: Prof Bryn Hubbard (Aberystwyth University), Dr Alex Brisbourne (British Antarctic Survey), Prof Bernd Kulessa (Swansea University)
CASE partner: Dr Ian Jones (ION GX Technology)
Main funding bodies
Fully funded NERC Industrial CASE award. Case partner ION GX Technology.
NERC Urgency Funding (2017) - Grant to travel to Antarctica to measure the Larsen C ice shelf stress response to large iceberg calving
INTERACT - TA (2017) - €3136 to assist fieldwork in Norway
IAMG Computers & Geosciences Research Scholarship. - $3333 to expand the scope of my PhD
Seismic surveys give insight into the physical properties of the englacial and subglacial properties of ice masses. Certain quantities, e.g. ice density, can be related to climate models and therefore provide proxies for the climatic evolution of a glacier (Kuipers Munneke et al., 2014; Hubbard et al., 2016). Such information is critical for predicting the stability of ice masses in a warming climate; these ice masses include the large ice shelves which fringe the Antarctic continent, widely believed to underpin the long-term contribution of Antarctic ice streams to global sea-level rise (DeContro and Pollard, 2016).
A major limitation of deriving density from seismic velocities is that velocity:density conversions are almost entirely empirical and therefore of questionable accuracy (Booth et al., 2013). The widely-applied Kohnen (1974) conversion is based on lab analysis of a South Pole ice core hence ice is removed from its original temperature/pressure context which, in any case, is likely different for other ice masses. While the general trend of density is likely characterised, greater confidence in the accuracy of inverted parameters would be beneficial. Full wavefrom inversion (FWI) of a seismic dataset (Virieux and Operto, 2009) represents a promising approach to property estimation that deserves investigation for glaciological applications.
FWI methods circumvent the need for empirical methods by deriving the underlying physical properties (seismic velocity, density, etc.) from the seismic wavefield itself. FWI has seen significant development in the hydrocarbons field (Brittan et al., 2013; Bai and Yingst, 2014; Jones, 2015), but its applicability in the glaciological setting is not widely proven. The development of FWI in glaciology would represent a step-change in seismic capabilities, which could be widely adopted throughout the community.
Ashmore DW et al., 2016. Firn heterogeneity of Larsen C Ice Shelf from borehole optical-televiewing. International Symposium on the Interactions between Ice Sheets and Glaciers within the Ocean, International Glaciological Society, La Jolla, 10-15th July 2016.
Bai J and Yingst D, 2014; Simulataneous inversion of velocity and density in time-domain full waveform inversion. 84th Annual International Meeting, SEG, Expanded Abstracts, 922-927.
Booth AD et al., 2013; A comparison of seismic and radar methods to establish the thickness and density of glacier snow cover. Annals of Glaciology, 54, 73-82.
Brittan J et al., 2013; Full waveform inversion – The state fo the art. First Break, 31, 75-81.
DeConto RM and Pollard D, 2016; Contribution of Antarctica to past and future sea-level rise. Nature, 531, 591-597.
Giesen RH and Oerlemans J, 2010; Response of the ice cap Hardangerjøkulen in southern Northay to the 20th and 21st century climates. Cryosphere, 4, 191-213.
Hubbard et al., 2016; Massive subsurface ice formed by refreezing of ice-shelf melt ponds; Nature Communications, 7, 11897.
Jones IF, 2015; Estimating subsurface parameter fields for seismic migration: velocity model building, in: Encyclopedia of Exploration Geophysics. SEG, pp. U1-1-U1-24. Editors: Vladimir Grechka and Kees Wapenaar.
Kohnen H, 1974; The temperature dependence of seismic waves in ice. Journal of Glaciology, 13, 144-147.
Kuipers Munneke P et al., 2014; Firn air depletion as a precursor of Antarctic ice-shelf collapse. Journal of Glaciology, 60(220), 205-214.
Kulessa B et al., 2016; Firn air-content of Larsen C Ice Shelf, Antarctic Peninsula, from seismic velocities, borehole surveys and firn modelling. EGU2016-4743, European Geosciences Union, Vienna, Austria.
Virieux and Operto, 2009; An overview of full waveform inversion in exploration geophysics. Geophysics, 74(6), WCC1-WCC26.
- MSci Geophysics, Imperial College London.
Research groups and institutes
- Institute of Applied Geoscience