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Department of Remote Sensing
Delft University of Technology
Kluyverweg 1, 2629 HS Delft
Netherlands
Phone: (+31) 15 278 2574
email: a.j.hooper@tudelft.nl
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Research Interests
My research interests lie in processes that cause deformation of the
crust, e.g., tectonics, volcanic systems and glacial isostatic adjustment.
A major limitation in our ability to model these
processes is the lack of deformation data in many areas and
much of my research effort is in developing new methods for detecting
deformation using Interferometric Synthetic Aperture Radar (InSAR) e.g.,
a new persistent scatterer method (see below), a new small baseline method, and
more recently a combined time series approach that brings togther both methods.
The other main thrust of my research involves using deformation data
to model volcanic and tectonic processes, such as magma chamber inflation/deflation
and slip on faults.
Many attempts to model volcanic processes still use relatively simple
models such as a point pressure source in a uniform halfspace. Although
valuable, our understanding of the underlying
processes can be enhanced by
incorporating increased complexity e.g.
variation of elastic properties and geometry, as well as moving
beyond kinematic models to models that make sense physically. My
preferred inversion approach is Bayesian, implemented with
Markov Chain Monte Carlo methods. This has the advantage of
providing the full a posteriori probability density for the model
parameters.
Current students
Anneleen Oyen, PhD, Constraining glacial isostatic adjustment in Antarctica using InSAR time series.
Joana Martins, PhD, Imaging the Torfajökull magma body using seismic and radar interferometry.
Qiang Wang, PhD, TBD.
Lennert van den Berg, MSc, Constraining glacial motion with a combination of laser altimetry and radar interferometry.
Naresh Soni, MSc, Phase unwrapping of seismic data.
Former students
Ye Yuan, MSc 2011, Measuring surface deformation caused by permafrost thawing using radar interferometry.
Karsten Spaans, MSc 2011, Deformation at Katla volcano, Iceland, 2003-2009.
David Bekaert, MSc 2011, InSAR time series analysis of the 2006 slow slip event on the Guerrero subduction zone, Mexico.
Persistent Scatterers
While conventional InSAR is a very effective technique for
measuring surface deformation, almost any interferogram includes
large areas where the signals decorrelate and no measurement is possible.
This decorrelation is due to the scattering properties of
resolution elements on the ground changing with time and/or viewing
angle. Consequently, most InSAR studies, to date, have focused on
areas that are dry and sparsely vegetated.
A relatively new analysis
technique, permanent scatterer InSAR, has been developed to overcome
the decorrelation problem by identifying resolution elements whose
echo is dominated by a single scatterer. This method has been successful
in the analysis of urban areas where angular buildings produce efficient
reflectors that dominate background scattering. However, man-made
structures are absent from most of the Earths surface. Furthermore,
in order to identify stable pixels this technique requires a priori
knowledge of how the deformation rate varies with time, whereas the
temporal nature of the deformation is usually one of the phenomena that
we wish to determine.
Working with colleagues, I have developed a new method of analysis that
uses spatial correlation of phase to find stable pixels in all terrains,
with or without buildings, without prior knowledge of deformation rate
variation. We refer to these pixels as persistent scatterers.
This method has now been applied by myself and others to
measure deformation due to various geophysical processes including
inflation/deflation of volcanoes, tectonic rifting, glacial isostatic rebound and postseismic relaxation.
The persistent scatterer software I have developed, known as StaMPS, can be downloaded
here.
The user group for this software is located
here.
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