A ground motion model for Spain
摘要
This paper proposes a Ground Motion Model (GMM) for horizontal spectral 5% damped accelerations for Spain. Firstly, a ground motion database is compiled from those of two public institutions, which contains earthquakes with magnitudes Mw between 3.0 and 6.0, and epicentral distances from 5 km to 300 km. The model is obtained by modifying a global GMM through the mixed-effects analysis of the residuals of the compiled database with respect to the global GMM. The model parameters adjusted are the anelastic coefficient in the path function and the linear magnitude scaling in the event function. The size of the database is insufficient for introducing changes in the site effect. The definition of the standard deviation is simplified: the within-event variability dependence is reduced to the spectral period, and the between-event variability keeps the analytical expression in the reference GMM and the reference values are calculated. The resulting model is compared with the starting GMM and with other regional models for Spain or previously applied in the region. The agreement with the reference GMM is good, the adjusted model presents higher values for periods between 0.1 s and 0.3 s, and the largest differences appear at distances above 100 km and for high periods. The existing regional models have limitations that preclude conducting some of the desirable comparisons, but the differences with those models are more important than those with the reference GMM.