Identification and Characterization of Discontinuities using Advanced InSAR Techniques
Giacomo Falorni, Bruce Macdonald, Jean Pascal Iannacone, Fabrizio Novali
Advanced InSAR techniques are capable of measuring and accurately characterizing ground deformation
due to their unique capacity to provide dense point clouds of deformation measurements coupled with
a history of movement over time. This information often highlights discontinuities or anomalies in
ground displacement patterns that can be caused by the surface expression of active faults or by the
opening of faults/fractures at depth. Ground deformation monitoring provides valuable input to the
study and characterization of discrete fracture networks in many different sectors. We will show here
applications related to the mining, oil and gas, and carbon capture and sequestration.
Open pit mines are often the site of significant ground deformation. This can be caused by the geometry
of the slopes and the steep gradients. The interaction of these factors with the geometry of the fracture
networks plays an important role in controlling deformation patterns. The use of recent satellites with
steerable beams allows all but the steepest pit slopes to be monitored by InSAR techniques as it is
possible to optimize the viewing angle and minimize areas not visible to the satellite. Typically pit walls
are reflective to the satellite signal and produce a high density of measurement points that provide a
detailed picture of ongoing slope deformations. This information accurately depicts the boundaries of
the movements, can highlight areas in which deformation trends change abruptly, identify if movement
is also occurring behind the pit crest and even highlight active faults within pits or their immediate
surroundings. We show several examples from operational open pit mines.
Over many producing reservoirs ground movement is induced by the production of hydrocarbons as well
as by enhanced recovery techniques. Detailed surface deformation observations can be used to identify
areas with strong differential movement, which often correspond to the surface expression of active
faults. We show an example in which a subsurface fault map derived from 3-D seismic imaging is
integrated with information on previously undetected active faults derived from advanced InSAR
processing to produce a comprehensive fault map.
In carbon capture and sequestration the integrity of the seal is a fundamental requisite for the safe
subterranean storage of CO2. Monitoring of surface deformation can provide valuable information on
the subsurface pressure field and act as an early warning system for potential leakages. We show an
example in which high resolution surface deformation monitoring provided the first indications of
problems with CO2 storage at a site and, coupled with geomechanical modeling, led to the suspension of
injection due to concerns of a potential CO2 to surface event.
There are many other fields in which a detailed overview of surface deformation has highlighted active
faulting, including the geothermal sector, fracking, gas storage, landslides and tunneling.