Satellite InSAR

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The group has an extensive capability to process satellite based Synthetic Aperture RADAR to derive interferograms of ground displacements associated with tectonic processes. We use these observations across the earthquake cycle from determining coseismic static offsets through generating postseismic time-series to the long-term measurements of the accumulation of interseismic strain. These observations are used to constrain the geometries of faults and their slip distributions, as well as probe the deeper crustal rheology and measure fault slip rates, with the aim of understanding landscape evolution and the distribution of seismic hazard. We have a long history of processing ESA’s C-band series of satellites from ERS in the nineties through ENVISAT to the latest Sentinel-1 images acquired today. We also have experience with RADASAT data as well as the ALOS L-band missions.

Satellite photogrammetry

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Many of our projects take advantage of the new generation of high-resolution optical satellite imaging to derive a detailed picture of the landscape. We use stereo-pairs of high-resolution satellite imagery to derive elevation models and quantify earthquake-related topography around the world. We have generated topographic models from imagery collected by several different satellites, including Digital Globe’s Worldview satellites, and Airbus Defence & Space’s Pléiades and SPOT satellites. These data enable detailed topographic analysis of near-field earthquake and tectonic deformation as well as secondary hazards such as landsliding.

Low-altitude/ground-based photogrammetry

helikite_photogrammetryWe use high-tech surveying techniques in the field in order to capture high-resolution, high-precision, high-accuracy topographic models of earthquake deformation. In particular we employ Structure-from-Motion techniques to generate 3D models from suites of overlapping photographs. Using anything we can think of to get our cameras up high, we capture low-altitude oblique aerial photos of landscapes and tectono-geomorphic features. Our group possesses two tethered helikites upon which we mount cameras. We also use unmanned aerial vehicles (UAVs–“drones”) to capture photos from above in systematic site surveys for geomorphic analysis.

 

Numerical Modeling of fault slip behavior

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We use different modeling strategies to look at the evolution of slip behavior along seismogenic faults.  Coupled with field and geodetic observations they are used to determine fault properties and to understand better the potential fault behaviors. This involves physics-based numerical models that incorporate all stages of the fault slip (coseismic, preseismic, postseismic). We also model the non-linear mechanical coupling between earthquake ruptures and the dynamically evolving off -fault medium (dynamic evolution of elastic moduli). Finally, we also explore the long term behavior of fault by developping 3-D linear Maxwell viscoelastic model (balance between the far-field loading, seismic redistribution of stress, and the viscous relaxation).