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Modélisation de la source sismique et sommation de petits séismes pour l'évaluation des mouvements forts: application à une meilleure estimation de l'aléa sismique dans le sud-est de la France

Abstract : Simulating strong ground motions produced by an earthquake is an important step to evaluate the seismic hazard of a region. The aim of this study is to provide an efficient tool for strong ground motions simulation.

To avoid the problem of unknown subsoil medium, we use the empirical Green's function technique. The ground motions are then obtained by summing the recordings of small earthquakes delayed between each other so as to reproduce the rupture propagation effects. The main problem of this study is to establish an appropriate summation scheme, which is able to generate realistic accelerograms in the time domain, and in agreement with scaling relationships (similarity relation and w-2 model) in the frequency domain.

Using statistical methods, we avoid the main problems encountered
classically in this kind of study. Finally, we establish two new methods of simulations: a purely stochastic method which requires the specification of only two parameters for the target event (seismic moment and stress drop) and a stochasto-kinematic method which is able to reproduce some of the kinematic rupture properties over the fault plane.



These two methods are successfully tested on observed data (Mexico and Italy). Then, the stochastic method is applied to simulate the ground motion which could be produced by two moderate sized earthquakes in the French Riviera: a magnitude 5.7 onshore earthquake (10 km to the north of Nice) and a magnitude 6.3 offshore earthquake (25 km to the south of Nice). These simulations point out three important points: (1) the strong amplification effects in some sites in Nice, (2) the importance of the ground motion potentially produced by a magnitude 5.7 onshore earthquake and (3) the major role played by the stress drop value of the potential earthquake.
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https://tel.archives-ouvertes.fr/tel-00011682
Contributor : Carine Kohrs-Sansorny <>
Submitted on : Friday, February 24, 2006 - 5:25:02 PM
Last modification on : Monday, October 12, 2020 - 11:10:19 AM
Long-term archiving on: : Saturday, April 3, 2010 - 8:22:19 PM

Identifiers

  • HAL Id : tel-00011682, version 1

Citation

Carine Kohrs-Sansorny. Modélisation de la source sismique et sommation de petits séismes pour l'évaluation des mouvements forts: application à une meilleure estimation de l'aléa sismique dans le sud-est de la France. Géophysique [physics.geo-ph]. Université Nice Sophia Antipolis, 2005. Français. ⟨tel-00011682⟩

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