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

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 Pb-210 and Cs-137 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.