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International audience; Variability of ground motion estimation according to various earthquake scenarios is studied in the region of the Sea of Marmara around Istanbul, Turkey, through numerical simulations using a 3D finite-difference method with CPU-GPU implementation. The earthquake scenarios dynamically simulated based on mechanical models are given with probability according to the geological, geophysical and seismological hypotheses. We adopt a 3D geological model of the Sea of Marmara taken into account of the basin structure (down to about 10 km depth) and the existence of the Sea layer (1.5 km depth at max.). Although beneath the land part around the Sea of Marmara is briefly a 1D structure, the influence of the 3D structure of the basin on the ground motion caused by the earthquakes along the North Anatolian fault is significant. Various earthquake scenarios of a magnitude of about 7 lead to a very heterogeneous ground motion pattern. For the selected points, we carry out statistical analysis on its characterization. In Istanbul area, a very strong ground motion (peak ground velocity larger than 1 m/s) may not be the most probable scenario, but has a probability of a few percents in the case where the stress drop is extremely high enough to lead to a super-shear rupture propagation.

The understanding of geology and petrophysical properties is necessary to develop deep geothermal projects. However, this knowledge must be shared within the French professional geothermal community to make the exploration process more efficient. Thermo2Pro is designed to fill the gap between the information derived from R&D projects and the authorities dealing with the deep geothermal exploration in basin context. Contracting authorities, local authorities, and design offices have been gathered in a user committee involved in the development of the project since its inception. The main vector for Thermo2Pro is a Web application where the user accesses the information by simulating vertical or horizontal sections, or boreholes. The information is stored in 3D regular grids derived from scientific projects. The functionalities of Thermo2Pro have been demonstrated through information related to the Trias aquifer of the Paris basin. In that area, the available parameters were mainly a model of geometry, an estimation of porosity, and a model of temperature. The Thermo2Pro project was dedicated to the development of the Web tool and its demonstration. The list of parameters available in Thermo2Pro is being expanded through the TRANS-CLAS project, by adding new information from the Paris basin and other areas such as Alsace and the French Massif Central. In addition, the use of data of the Dogger reservoir in the Paris basin is under study. Thermo2Pro and TRANS-CLAS are co-financed by the ADEME (French Environment and Energy Management Agency) and BRGM (French Geological Survey). The parameters used in Thermo2Pro have been acquired and inferred in the scope of the CLASTIQ-2 project co-financed by the ADEME and BRGM.

It is well known that a better understanding of the geology and petrophysical properties is necessary to develop deep geothermal projects. However, this knowledge must be shared within the professional community to be efficient. Thermo2Pro is essentially a Web tool designed to fill the gap between the information derived from R&D projects and the authorities of the geothermal sector who need to use it. Thermo2Pro is a joint project lead by ADEME and BRGM - the French Environment and Energy Management Agency, and the French Geological Survey -. It is dedicated to professionals dealing with the deep geothermal exploration in basin context. A user committee, gathering contracting authorities, local authorities, and design offices, has been involved in the development of the project since its very beginning. Thermo2Pro has two main objectives: to give relevant material to prepare a pre-feasibility study, and to promote geothermal development by facilitating access to the information. The main vector for Thermo2Pro is a Web application where the user accesses the information by simulating vertical or horizontal sections and boreholes. Requests are defined via an interactive cartographic interface running WPS Web services (Web Processing Service, OGC - Open Geospatial Consortium). Data are kept in 3D grids allowing a management of the information in a standard way; staying independent from the tools that have generated this information. The 3D grids are stored in a VTK format (Visualization Tool Kit). The functionalities of Thermo2Pro will be demonstrated through data related to the Trias aquifer of the Paris basin. This reservoir could be a complement to the Dogger that has been exploited since the 80's in the area. The available information for the Trias will be mainly a model of geometry, an estimation of porosity, and a model of temperatures. Those parameters have been acquired and inferred in the scope of the CLASTIQ-2 R&D project (ADEME and BRGM).

International audience

International audience

International audience

International audience

International audience

International audience

International audience; We accelerate a three-dimensional finite-difference in the time domain (FDTD) wave propagation code by a factor between about 20 and 60 compared to a serial implementation using Graphics Processing Unit (GPU) computing on NVIDIA graphics cards with the CUDA programming language. We describe the implementation of the code in CUDA to simulate the propagation of seismic waves in a heterogeneous elastic medium. We also implement Convolution Perfectly Matched Layers (CPMLs) on the graphics cards to efficiently absorb outgoing waves on the fictitious edges of the grid. We show that the code that runs on a graphics card gives the expected results by comparing our results to those obtained by running the same simulation on a classical processor core. The methodology that we present can be used for Maxwell's equations as well because their form is similar to that of the seismic wave equation written in velocity vector and stress tensor.