Exploring the feasibility of an early warning system in a moderate seismicity context: case study of Pyrenees

Abstract : Pyrenees presents a moderate seismicity responsible of many destructive earthquakes over history, which maximum magnitude could probably reach 6.5. This seismicity has led to the development of seismological forecasting networks around the massif. In this context, a feasibility study of a Pyrenean earthquake early warning system (EEW) had been performed within the framework of the SISPyr project. We first focused on "technical" feasibility aspects. Then, the SISPyr seismic network had been examined in order to assess its adaptability to early warning purposes. Then different rapid magnitude determination methodologies have been tested in order to check their adaptability to the Pyrenean context and to establish empirical relationships usable in Pyrenees. To that end, a waveform catalog had been constituted. The analysis of these records has allowed us to bringing to light clear correlations between earthquakes' magnitudes and four waveforms indicators calculated from first seconds of the P wave. We also considered question of the opportunity to put in place EEW in Pyrenees. As to do that, an analysis of theoretical performances of the system had been performed. Furthermore, this simplified approach can guide definition of potential uses of Pyrenean early-warnings, since they are closely dependant to the time separating warning arrival to the one of destructive seismic-waves. Finally, we carried through a survey bound to Pyrenean potential end-users in order to evaluate their wishes in terms of earthquake early warning.