SISCOR

The SISCOR project aims at providing new, key observations and improved methodologies for contributing to refine the prediction laws and the physical models of earthquake generation and fault activity, including transients, at various space and time scales. The selected area is the western rift of Corinth (Greece), one of the most active seismic region in Europe, where destructive earthquakes are expected in the coming decades. This area has been the focus of intense French and European research for the last 20 years, combining seismology, geodesy, tectonics, sedimentology, geophysics,…). This motivated in 2000 the launch of the Corinth Rift Laboratory (CRL), strongly supported by CNRS/INSU and French laboratories, and by E.C.. In 2009, it has been recognized by INSU as a “site intrumenté” for long term monitoring. The SISCOR project will allow a qualitative jump in the understanding and the resolution of the mechanical processes at the CRL. It brings together the multi-disciplinary expertise of 6 main Institutions (IPGP, ENS, GEOAZUR, IRSN, CRPG, LGCA), with collaboration with foreign groups (Belgium, Greece, Italy, G. Britain). The project is subdived into 4 main research Tasks. Task 1 is dedicated to the acquisition and analysis of “short-medium term” data (seconds to decades). Geodetic surveys (GPS and range) and continuous seismic and geodesy (GPS, tiltmeters, strainmeters) monitoring will characterize the puzzling, reported intermittent creep activity of one of the major faults. Data analysis from the whole CRL data base will provide clues for constraining the space-time fluctuation of microseismicity, strain transients (creep, pore pressure migration) and their coupling with seismicity, 3D fault geometries , and locked and slipping areas of the faults. Task 2 is dedicated to the acquisition and analysis of “long term” data (decades-500 Kyrs). Dates, magnitude, and location of past large earthquakes in the area will be searched for in order to provide an earthquake catalogue (M>6) as long and complete as possible. This will be achieved through historical archive research, archeological studies, and turbidite indentification is offshore sediments. The latter will require marine investigation in the gulf with seismics and shallow coring. The evolution of the fault system since -500 Kyrs will be investigated, with field studies, in order to understand and constrain the locking, growth, or re-activation of some fault segments, and the average slip rate of the major faults will be determined. Task 3 is dedicated to the 3D modelling of the recorded data. Firstly, 3D kinematic models will be proposed, integrating multi-scale data and models from Tasks 1 and 2. Then, various 3D mechanical models will be developed. The kinematic model will be the input for a numerical modelling of the crust with seismic faults and non elastic rheology, aimed at producing synthetic sequences of large earthquakes over 10 Kyr. Cross-triggering laws will be constrained by the historical earthquakes of the rift, and the dynamic rupture across fault segments will be investigated with models with rate and state (RS) friction laws. A RS model with interacting asperities on a creeping fault surface will be developed. Task 4 is dedicated to the quantification of the likelihood of future earthquakes, on or around the major faults. It will be based on results produced by Tasks 1, 2 , and 3. It will make time-independent assessments, i.e., ignoring the date of the last earthquake on each fault, as well as time dependent assessments, i.,e. taking into account on each fault the strain accumulation since the last earthquake. It will also integrate the possibility of cascading earthquakes, an event possibly triggering another one. All these studies will be based on a logic tree approach, for taking into account the uncertainties on data and models, and their relative weights provided by experts.