Onshore-Offshore active tectonics along the Carboneras Fault Zone (Eastern Betic Cordilleras)

Abstract

The onshore-offshore Carboneras Fault Zone (CFZ), located along the Eastern Betics Shear Zone, is described and analyzed with the aim of establishing its seismic potential. Bathymetry and seismic profiles show a large variability of transpressive structures along the fault zone coinciding with onshore structures. Both onshore and offshore studies show faulted Quaternary layers and mass movement deposits related to paleoearthquakes suggesting that the CFZ is seismogenic. Analysis of the onshore-offshore fault geomorphology and of the paleoearthquake deposits in trenches allows us to obtain some of the paleoseismic parameters. Based on this data, we infer that the CFZ is a slow structure with minimum recurrence periods of 13.5 ka, minimum strike-slip rates of 0.6 mm/a and dip-slip rates between 0.05 mm/a and 0.16 mm/a. Onshore, a faulted and buried paleochannel constrains the last earthquake to AD 772-889. Empirical relationships allow for the estimation of maximum earthquake magnitudes (Mw) of 7.4 for the northern segment, 6.8 for the central segment and 6.2 for the southern segment