Identifying instrumental and historical earthquake records in the SW Iberian margin using ²¹⁰Pb turbidite chronology

Abstract

Textural, mineralogical and geochemical analyses of near‐surface sediments from six different stations offshore SW Iberian Peninsula revealed the presence of thin detrital intervals corresponding to very fine‐grained turbidites. Precise dating of the two most recent sedimentary layers based on 210 Pb and 137 Cs geochronology provides ages of 1971 ± 3 AD and 1908 ± 8 AD. These ages correspond to high‐magnitude historical and instrumental earthquakes that occurred in the region: the 1969 Horseshoe Earthquake (Mw 8.0) and the 1909 Benavente Earthquake (Mw 6.0). Such a good correlation between turbidites and high‐magnitude (Mw > 6) historical and instrumental seismic events suggests that the record of mass transport deposits can also be used as a paleoseismic indicator in low‐convergence margins.