Morphotectonics (high resolution / LIDAR) and paleoseismology of theTrevaresse Fault (FACT axis Region 2 working group)
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14 septembre 2021
- handle: 10670/1.k1qx1u
- halshs: halshs-04319947
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Active faults Provence LiDAR paleoseismologySujets proches
Laser radar LidarCiter ce document
Magali Rizza et al., « Morphotectonics (high resolution / LIDAR) and paleoseismology of theTrevaresse Fault (FACT axis Region 2 working group) », HAL-SHS : géographie, ID : 10670/1.k1qx1u
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This research project is part of the "Active faults - France" (FACT) action carried out by the RESIFconsortium, one of whose objectives is to better understand seismotectonics and processes thatcontrol active deformation and seismic hazard in metropolitan France. In addition, the FACT actionalso aims to improve the temporal resolution of past earthquakes by developing paleoseismologicalinvestigations (trenches in Quaternary deposits), involving also sub-surface geophysical methods tolocate potentially active structures under Quaternary sedimentary deposits. Within the framework ofthe RESIF consortium, we wish to re-launch work in Provence, which is one of the target areas of theFACT action and for which CEREGE is the regional coordinator (region 2).One of the proposed axes of our research project is to continue morphotectonic analyses in Provenceby using new tools of very high resolution topography such as LiDAR imagery or SfM photogrammetryby drone. We first focus on the Trévaresse fault, whose historical reactivation was responsible for theLambesc earthquake in 1909, one of the most destructive shaking in recent history in France, withstrong damage to the villages. One of the advantages of this study area is that the morphology, surfacerupture and fault segmentation associated with the activity of the geological structures have beenpartly evidenced by studies in the 2000s (Chardon & Bellier., 2003). Moreover, the surface rupture ofthe 1909 earthquake was identified in an open trench (Chardon et al., 2005) and the quaternarysediments excavated there were affected by multiple earthquakes. However, none of the formationsin this trench have been dated and we therefore have no knowledge of the return times on this faultsystem.Our objective is to refine first the mapping of quaternary morphological surfaces and tectonic scarps.In 2021, our work focused on the morphological expression of active fault segments andgeomorphological anomalies identified by exploiting high-resolution (1 meter) topography surveyedwith airborne LiDAR by a team from the University of Caen (Thomas, 2018). These data have beencomplemented by field observations and new structural geology data and some geophysical surveys.In addition, photogrammetric surveys by drones were performed to complete very high-resolutiontopographic data (