Advertisement posted by Sheila Peacock - on my own account,
not as list owner.

Please draw to the attention of any suitable (home or EU) candidates.

Thank you.
Sheila Peacock.


University of Birmingham
Earth Sciences
School of Geography, Earth and Environmental Sciences

NERC CASE Research Studentship
with Veritas DGC

Seismic anisotropy in hydrate- and gas- bearing sediments, and
continental slope stability

The presence of methane hydrate in continental margins and its
associated zone of free gas is widely cited as an important control on
the formation of submarine slides, and the dissociation of hydrate to
free gas has been invoked as a cause of slides.  The release of
methane gas from submarine slides is believed to be an important
source of methane input to the atmosphere during periods of global
warming.  The presence of hydrate is commonly revealed by the
occurrence of a bottom-simulating seismic reflector (BSR), formed at
the boundary between hydrate-bearing sediment above and sediment
containing a small percentage of free gas held in pore spaces by
surface tension.  Down-slope stresses on continental slopes create
fractures and faults that run parallel to the contours of the slope
and can, in places, be imaged with seismic sections, such as in the
region of the Storegga slide, off Norway, one of the world's largest
submarine slides, which occurred about 8,000 years BP.  As part of its
programme of data acquisition in July, 2002, a European Commission
Framework 5 Project, HYDRATECH, which is co-ordinated by the
University of Birmingham, conducted seismic experiments with two
arrays of ocean-bottom seismometers, 21 in each array, on the northern
flank of the Storegga Slide off Norway, where a BSR of varying
character is shown well by existing seismic reflection data.  The
region of these experiments, in water depths of 900-1200 m, was also
covered by a high resolution 3D seismic reflection survey.

The primary aim of the PhD project will be to define the degree and
kind of anisotropy present in the sediment column from the seabed
through the zones containing hydrate and gas.  The effect of varying
hydrate and gas concentration in thin layering will be to produce a
vertical or tilted transverse isotropy, whereas the effect of cracks
caused by down-slope stresses will be to produce azimuthal anisotropy.
The experiment was designed to be able to distinguish between
azimuthally dependent and offset-dependent variations and to
distinguish anisotropy from heterogeneity.  The primary approach will
be to derive the anisotropy from model-based inversion of the travel
times of P waves and P-S converted waves. There is a strong contrast
in Poisson's ratio across the BSR, and it is probable that the effect
of anisotropy will be also exhibited by azimuthal variation in the AVA
response of reflections from the BSR.  The final phase of the project
will evaluate the relationship between the seismic anisotropy and the
faulting and fracturing imaged by the high resolution 3D seismic
reflection survey, and other evidence of slope failure.

Research training will be augmented by training in seismology and
seismic data processing, as well as in the project-specific techniques
and software.  At Veritas DGC, the student will gain experience of
working with industry software and more general aspects of the use of
4-component data in reservoir characterisation through the group in
which he or she will work.  The research supervisors are Professor
Graham Westbrook and Dr Sheila Peacock at the University of
Birmingham, and Dr Shuki Ronen at Veritas DGC.

The studentship, which is for UK residents, is provided by NERC
through its Ocean Margins LINK Programme.  It is for a duration three
years, and can be begun on any date up to 1st October 2003.  [The
studentship can be held by an EU student, but only the cost of fees
will be supported.]  Applications and enquiries should be made to
Professor Graham Westbrook, as soon as possible, but by 23rd June 2003
at the latest. On-line application can be made at
http://www.bham.ac.uk/application/, although initial application can
be by letter, accompanied by a curriculum vitae and the names of two
academic referees, to Professor Westbrook, Earth Sciences, School of
Geography, Earth and Environmental Sciences, University of Birmingham,
Edgbaston, Birmingham B15 2TT, or [log in to unmask]