Earthquake surface ruptures, paleo-earthquake time series, as well as geometry,
growth and propagation of active faults have long been major points of interest of our lab. We now explore in more depth the factors that control the geometry
and kinematics of fault systems, growing from their initiation to the organization of large scale
structures. One important focus is the reciprocal interactions between successive
earthquakes and the evolution of fault geometry; for example, how dynamic rupture affects
fault geometry through damage or branching, or how fault geometry may control earthquake
rupture and the occurrence of earthquake sequences.
High-resolution maps of the surface fault traces obtained by combining field observations and satellite imagery reveal the geometric complexity of rupture. Detailed earthquake source imaging suggests that such complexity is not only an effect of the free surface, but that it also exists at depth. Recent work has shown that if the dataset becomes large enough, one can start to identify generic properties for fault systems that should be of use in further modeling efforts. We aim to develop a dataset of detailed field observations, including earthquake rupture geometry and time series of past earthquakes, that will be implemented in a set of models describing the nucleation of faults and their temporal geometric evolution at different scales of space and time.
We use the new possibilities from the submetric optical satellite images, as well as high resolution topographic data acquired from these images, field photogrammetry or Lidar techniques, to accurately map fault and rupture geometry. When possible, the slip distributions is determined and field-work is conducted to cross-check key observations against the images and to establish earthquake time series using paleo-seismology. In the near future, the rapid repetition of image acquisitions and geodetic techniques, based on In- SAR and image correlations, as well as seismic activity monitoring, will allow to dynamically map the evolution of elastic and permanent strains on active faults, which are in some case coeval with magma intrusion like in the Afar. Besides, key geological observations and dating of markers is used to constrain how faults have evolved and propagated at larger times cales, then to constrain mechanical models of fault growth and interaction at crustal / lithospheric scale.