Kinematics and Seismic Behavior of Active Faults in Strike-Slip and Collisional Settings: Application to the Dead Sea Fault and to the Southern Western Foothills of the Taiwan Mountain Belt(3/3)

Understanding the kinematics and seismic behavior of active faults is critical to better assessseismic hazard and take it into account for people’s lives and infrastructures development. Here are themain questions that active tectonics studies aim at answering. How do fault kinematics evolve withtime and what is the mechanism behind it? How do large earthquakes (M>6.5) distribute in time andspace? The broad objective of this project is to gather more observations about active faults using amultiple-timescale and multi-disciplinary approach on two different types of tectonic setting: a majorstrike-slip fault located in the Eastern Mediterranean, the Dead Sea fault, and active thrusts at thepiedmont of the Taiwan fold-and-thrust belt, in Tainan area.On the Dead Sea fault, we target a fault segment where fault slip rates are already welldocumented and where the paleo-earthquake time distribution was already observed at one site. Wepropose to examine the paleo-earthquake time distribution at a second trench site, several 10 km away,in order to estimate the length of paleo-ruptures, identify barriers to the rupture propagation, andobserve how fault segments interact. In a next step, we aim at determining the amount of coseismicslip for each paleo-earthquake by matching buried channels on either side of the fault. Then, we willbe able to discuss the fault seismic behavior, between time-predictable model and slip-predictablemodel.The southern part of the Western Foothills of Taiwan accommodates ~45 mm/yr of shortening,across structures that are still largely unknown today. Taking advantage of new geodetic data as wellas unpublished subsurface data, we propose to draw a series of balanced cross-sections from theCoastal Plain to the Pingtung Plain at the latitude of Tainan. We aim at identifying the activestructures, including buried folds within the Coastal Plain, characterize their geometry, determine theirtotal shortening, and ideally their shortening rate at different timescales. Thanks to publishedmagnetostratigraphy and nannostratigraphy, we expected to be able to discuss the evolution of thefold-and-thrust belt in the early stage of its formation.