Shallow structure of Andalucia (Southern Spain) and Alborán Sea from short-period Rayleigh waves
M. Chourak, M. Navarro, V. Corchete and J. I. Badae
Event name: 4th EEGS Meeting
Session: Land & marine seismics
Publication date: 14 September 1998
Info: Extended abstract, PDF ( 408.22Kb )
Price: € 20
Up to now, dispersion analysis of surface waves at the short period across the southem region of the Iberian peninsula has never been investigated. In this study, group velocity dispersion was deterrnined for Rayleigh waves between of 1.5 and 6.0 s generated by local earthquakes in sourthem of Spain and Alboran sea (mediterranean sea). A total of 18 seismie events were studied occured between 1990 and 1995. The events were recorded at a single component station belonging to the Regional seismie Network of Andalucia. To remove higher-move interference efficiently and to impore isolation of the fundamentalmode Rayleigh wave from the seismograms, time-variable filtering is employed. Once the signal, multiple filtered is then used to compute group veloeities in each station. We carried out inversion of velocity dispersion data containing Rayleigh-wave group veloeities according to the generalized inversion theory by means of the stochastic inversion operator. We have obtained shear velocity value beteween 0 and 4 Km.The paths of these surface waves go throw various geologie structures, and different dispersion regions have been identified. The inversion results suggest the existence of some degree of lateral variation of shear wave velocity in the region and we observed a good correlation between those changes and the contrasting geology between adjacent geological forrnation.