TY - JOUR T1 - Holocene earthquake record offshore Portugal (SW Iberia): testing turbidite paleoseismology in a slow-convergence margin JF - Quaternary Science Reviews Y1 - 2010 A1 - Gracia, Eulalia A1 - Vizcaino, Alexis A1 - Escutia, Carlota A1 - Asioli, Alessandra A1 - Rodes, Angel A1 - Pallas, Raimon A1 - Garcia-Orellana, Jordi A1 - Lebreiro, Susana A1 - Goldfinger, Chris AB - The SW margin of the Iberian Peninsula hosts the present-day boundary between the Eurasian and African Plates. Convergence (4-5 mm/yr) is accommodated through a wide deformation zone characterized by moderate magnitude seismic activity. This zone has also been the source of the most important seismic events in Western Europe, such as the 1755 Lisbon Earthquake and Tsunami and 1969 Horseshoe Earthquake. Despite efforts to identify active seismogenic structures in the Gulf of Cadiz in the last ten years, little is known about its paleoseismic history. The turbidite paleoseismology approach was applied for the first time in a low-rate convergent margin to determine the recurrence interval of large earthquake events that occurred in SW Iberia during the Holocene. Four sediment cores collected at strategically located sites offshore Portugal (i.e. Tagus Abyssal Plain, Infante Don Henrique Basin and Horseshoe Abyssal Plain) reveal that these deep-sea basins preserve a record of episodic deposition of turbidites. In the SW Iberian Margin excluding special climatic events, earthquakes are the most likely triggering mechanism for synchronous, widely-spaced distributed turbidites during the Holocene, when the sea level was relatively stable. Age correlation together with textural, mineralogical, physical properties and geochemical signatures of the new cores complemented by pre-existing multicores and gravity cores reveals a total of 7 widespread turbidite events for the Holocene. Precise dating of the most recent turbidite event (E1) based on (210)Pb and (137)Cs geochronology provides an age of AD 1971 +/- 3. This age corresponds to a high-magnitude instrumental earthquake in the region: the 1969 Horseshoe Earthquake (Mw 8.0). Calibrated (14)C ages of subsequent widespread turbidite events (E3 and E5) correlate with the dates of important historical earthquakes and paleotsunami deposits in the Gulf of Cadiz area, such as AD 1755 and 218 BC, respectively. If older synchronous events (E6, E8, and E10) with ages ranging from 4960-5510 yr BP to 8715-9015 yr BP are also taken into account, a great earthquake recurrence interval of about 1800 years is obtained for the Holocene. Our correlations suggest that the turbidite record may be considered as a proxy for paleoseismic activity in low-convergence rate margins, and a valuable complementary tool in earthquake and tsunami hazard assessment along the coasts of the Iberian Peninsula and North Africa. (C) 2010 Elsevier Ltd. All rights reserved. VL - 29 IS - 9-10 N1 - id: 1959; PT: J; UT: WOS:000277813300008 JO - Holocene earthquake record offshore Portugal (SW Iberia): testing turbidite paleoseismology in a slow-convergence margin ER - TY - JOUR T1 - Sedimentology, physical properties and age of mass transport deposits associated with the Marques de Pombal Fault, Southwest Portuguese Margin JF - Norwegian Journal of Geology Y1 - 2006 A1 - Vizcaino, Alexis A1 - Gracia, Eulalia A1 - Pallas, Raimon A1 - Garcia-Orellana, Jordi A1 - Escutia, Carlota A1 - Casas, David A1 - Willmott, Veronica A1 - Diez, Susana A1 - Asioli, Alessandra A1 - Danobeitia, Juanjo VL - 86 N1 - id: 623 ER -