Testing the Earthquake Early-Warning Parameter Correlations in the Southern Iberian Peninsula

The south of the Iberian Peninsula is of especial interest for the application of Earthquake Early Warning System (EEWS) technologies due to the past occurrence of damaging earthquakes such as the 1755 Lisbon earthquake. However, there are several critical issues that need to be addressed in order to develop an EEWS in this area. The first is the magnitude scale inhomogeneity of the available catalogues. A second is that most of the available broad-band seismograms for this area correspond to earthquakes with magnitudes less than 6.0, recorded at distances greater than 100 km, and sometimes with a low signal-to-noise ratio. And third, the occurrence of large earthquakes in this area means that the standard EEWS time window normally used needs to be tested in order to check whether it is long enough. Our paper describes the results of homogenizing the catalogue magnitudes by using empirical relationships to obtain the moment magnitude M-w. A criterion based on a threshold value for the signal-to-noise ratio is applied in order to avoid noise-contaminated seismogram data. An important part of the study is a check of whether the correlations previously obtained for south Iberia are valid for other neighbouring areas such as Algeria, and for larger earthquakes. Finally, since recent studies have shown that the larger the earthquake the longer the time window needed to properly estimate the magnitude, the window was increased progressively from 0 to 20 s in order to study the behaviour of the EEWS parameters for the largest earthquakes in the database.