Physics-Based Broadband Ground Motion Simulations in Near Fault Conditions: the L'Aquila (Italy) and the Upper Rhine Graben (France-Germany) Case of Studies
Abstract
Predictions of realistic ground motion for potential future earthquakes are always an interesting task for seismologists and are also the main objective of seismic hazard assessment. While, on one hand, numerical simulations have become more and more accurate and several different techniques have been developed, on the other hand ground motion prediction equations (GMPEs) have become a powerful instrument (due to great improvement of seismic strong motion networks providing a large amount of data). Nevertheless GMPEs do not represent the whole variety of source processes and this can lead to incorrect estimates especially in the near fault conditions because of the lack of records of large earthquakes at short distances. In such cases, physics-based ground motion simulations can be a valid tool to complement prediction equations for scenario studies, provided that both source and propagation are accurately described. We present here a comparison between numerical simulations performed in near fault conditions using two different kinematic source models, which are based on different assumptions and parameterizations: the "k-2 model" and the "fractal model". Wave propagation is taken into account using hybrid Green's function (HGF), which consists in coupling numerical Green's function with an empirical Green's function (EGF) approach. The advantage of this technique is that it does not require a very detailed knowledge of the propagation medium, but requires availability of high quality records of small earthquakes in the target area. The first application we show is on L'Aquila 2009 M 6.3 earthquake, where the main event records provide a benchmark for the synthetic waveforms. Here we can clearly observe which are the limitations of these techniques and investigate which are the physical parameters that are effectively controlling the ground motion level. The second application is a blind test on Upper Rhine Graben (URG) where active faults producing micro seismic activity are very close to sites of interest needing a careful investigation of seismic hazard. Finally we will perform a probabilistic seismic hazard analysis (PSHA) for the URG using numerical simulations to define input ground motion for different scenarios and compare them with a classical probabilistic study based on GMPEs.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.S31C2772D
- Keywords:
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- 5104 Fracture and flow;
- PHYSICAL PROPERTIES OF ROCKSDE: 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGYDE: 7215 Earthquake source observations;
- SEISMOLOGYDE: 7290 Computational seismology;
- SEISMOLOGY