Task 3: Estimating Ground Motions from generic rupture models and assessing uncertainties
Leader: Fabian BONILLA (IFSTTAR) – Partners involved: IFSTTAR, ENS, IRSN, Géoazur, Centrale, Caltech, ETH
The Task 3 of the project aims at examining whether the more accurate descriptions of the fault sources that we provide in this project are key information to significantly improve the Ground Motion estimates. We also seek to understand the contribution of the fault source representation on the computed Ground Motion uncertainties. Integrating details on the fault source has not been done so far in Ground Motion simulations.
Ground Motions will be computed from the generic 3D source models produced in Task 2. The target frequency will first be around 1 Hz to reduce computation time. Later, the modeling with smaller scales of fault segmentation should guide us to understand better the origin of the higher frequencies produced by the source, and hence to run the rupture models up to 10 Hz. In both cases, the computed dynamic stress and strain fields will be introduced in the 2D, non-linear, P-SV/SH codes that we have already developed (3D implementation in progress), so as to simulate Ground Motions in realistic nonlinear media and soils.
Simultaneoully with the previous actions, we will study the nature of the observed uncertainty on the Ground Motions. For large earthquakes, the causative fault is generally identified, and therefore the impact of its properties onto the produced Ground Motions can be examined.