Similitudes entre la actividad sísmica actual y la paleosismicidad durante el Mioceno Superior en las zonas externas de las Cordilleras Béticas: restricciones a partir del parámetro "b"

Resum

Several measurements dealing with the "b" parameter in a work area were carried out to find a relationship between palaeoseismic data and instrumental seismic records. The palaeoseismic data series were obtained by analysis of «mixed layers» (deformational geological structures by seismic activity) in varved sediments of three Neogene lacustrine basins near Hellín (Albacete): El Cenajo, Elche de la Sierra and Híjar. These seismic structures were dated (relative values) by recognition of cyclic annual sedimentation in varved sediments. Therefore, we could established the recurrence interval of 130 years for palaeoearthquakes's magnitude (Mb) 4 of minimum value, for an interval of 9500 years. The "b" parameter of instrumental seismic records in the Betic Chain has been calculated by several authors according to different zonation far time intervals and a value between 0.86 and 1.0 was obtained. The working area presents a similar value of "b" parameter in palaeoseismic records and instrumental seismic data. This value is close to 0.86. Both seismic processes o bey to the Gutenberg-Richter's law and we have considered that this represents a good relationship between palaeoseismic and instrumental data in this area.