Elsevier

Quaternary International

Volume 242, Issue 1, 1 October 2011, Pages 196-200
Quaternary International

Holocene palaeotsunami catalogue of SW Iberia

https://doi.org/10.1016/j.quaint.2011.01.036Get rights and content

Abstract

Many on-shore studies focused on high energy marine events occurred in the Gulf of Cadiz have been published since the 1990s. Most of the findings came from sedimentary, palaeontological and geomorphological records on estuaries, marshes, beach-barriers (spit-bars), and some coastal lowlands. Recent off-shore investigations in SW Iberia considered turbidite deposits as a proxy to recognise palaeoearthquakes in this zone. The comparison of datasets from both on-shore and off-shore records indicate that at least five tsunami events generated by strong earthquakes affected this area during the last 7000 years, previous to the more recent and well-documented 1755 AD Lisbon earthquake tsunami event. The catalogue of Holocene palaeotsunami presented here is supported by geological and geomorphological evidences, but also for archaeoseismic and palaeoseismic evidence and written reports for the more recent events occurred during historical times. The recurrence interval for these catastrophic events can be bracketed between 1200 and 1500 years.

Introduction

Seismic activity in the Gulf of Cadiz appears to be related to Azores–Gibraltar transform fault zone (Gloria Fault). The tectonic pattern of this area operates as a strike-slip movement in the western part (Azores) and as a north–south compression to the east (Gibraltar) (Udías et al., 1976, Buforn et al., 1988). Commonly, the 1755 Lisbon earthquake epicentre has been located 200 km southwest of San Vicente Cape (Fukao, 1973, Martínez Solares et al., 1979). Recently, however, drill core and seismic profile data suggest an incipient subduction area west of Portugal where the tsunami origin may possibly have been located (Baptista et al., 1998, Zitellini et al., 1999, Zitellini et al., 2001). Data from off-shore southern Portugal revealed a number of active faults that may represent an earthquake and tsunami hazard to the coast of SW Iberia and NW Africa (Gràcia et al., 2003a, Gràcia et al., 2003b, Gràcia et al., 2010, Terrinha et al., 2003, Zitellini et al., 2004).

Off-shore studies are related to multidisciplinary marine geological and geophysical campaigns focused on the study of the active tectonics of SW Iberia. Recent papers have tried to highlight the potential of the turbidite record as a marine palaeoseismic indicator, as well as the correlation with the on-shore tsunamites record (Garcia-Orellana et al., 2006, Vizcaino et al., 2006, Gràcia et al., 2010).

The studies focused on on-shore record of these events have also attempted to distinguish features produced by tsunami and other extreme wave events (EWE), such as severe storm surges (Lario et al., 2010). Most surveys of EWEs in the area have concentrated on: Guadalquivir (Lario et al., 1995, Lario et al., 2001a, Lario et al., 2001b, Lario, 1996, Ruiz et al., 2004, Ruiz et al., 2005, Cáceres et al., 2006), Tinto-Odiel (Lario, 1996, Ruiz et al., 2007, Morales et al., 2008), and Guadalete (Lario et al., 1995, Lario, 1996, Dabrio et al., 1999, Luque et al., 2001, Luque et al., 2002) estuaries, the littoral lowland on the south-eastern coast of the Gulf of Cadiz (Luque, 2002, Whelan and Kelletat, 2003, Whelan and Kelletat, 2005, Alonso et al., 2004, Luque et al., 2004), and the Algarve (Andrade, 1992, Dawson et al., 1996) (Fig. 1). These studies described the sedimentary record of high energy events in the Gulf of Cadiz and concluded that most of them were tsunamigenic in origin. Following this conclusion, recurrence intervals were deduced (Morales et al., 2008, Ruiz et al., 2008a). The reported sediments are usually interbedded in estuarine or spit barrier sedimentary units that act as effective sedimentary sinks, likely to preserve geomorphological features that witness the palaeoenvironmental changes. Lario et al. (2010) summarised these studies and concluded that destructive events in this area created by EWE have a periodicity of 1200–1500 y, but not all were generated by tsunamigenic events.

Section snippets

Off-shore record of earthquake-triggered turbidites

Although some work suggested the presence of earthquake-triggered turbidites in this area (Thomson and Weaver, 1994, Lebreiro et al., 1997) it was only recently that the first paper about turbidite seismology in the SW Iberian margin appeared, studying the sediments related to 20th century earthquakes (Garcia-Orellana et al., 2006). Vizcaino et al. (2006) studied four gravity cores and found some events recorded as debris flows and turbidites that allowed estimation of a recurrence interval of

Record of EWE on-shore

Geomorphological and sedimentological features generated by extreme wave events (EWE) are common along the coasts of the Gulf of Cadiz, and have been assigned to either tsunami or storm surges (Lario et al., 2010). During recent years, numerous studies have tried to characterise the sedimentological features of tsunami and storm events, and concluded that the deposits generated by both types of events exhibit similar textural, structural and sedimentary properties (Morton et al., 2007, Morton

Discussion: on-shore evidence of palaeotsunami and their correlation with the off-shore record

The record of earthquake-triggered turbidites off-shore in this area (Gràcia et al., 2010) and the extreme wave events (EWE) that reached the SW coast of Iberia (Lario et al., 2010) allow correlation of these events, assignment of a tsunamigenic origin to some of the off-shore deposits, and identification of those regional events affecting the entire study area, generated by seismic sources in the Gulf of Cadiz area (Fig. 2).

The oldest EWE is recorded in Valdelagrana spit barrier system (Lario,

Conclusions: on-shore catalogue of palaeotsunami and recurrence intervals

Comparison of the on-shore geological record with the recently published off-shore records of palaeotsunami in the SW coastal area of the Iberian Peninsula (Gulf of Cadiz) makes it possible to identify five main EWE’s generated by tsunami affecting the area for the last 7000 y, prior to the well-known 1755 Lisbon tsunami-earthquake. These five events have calibrated ages of ca.7000–6800 cal BP, ca.5500–5000 cal BP, ca. 3900–3600 cal BP and ca.2200–2000 cal BP (Fig. 2), consistent with the

Acknowledgements

The research was funded by Projects EU NEAREST, CGL-2008-4000/BTE, CGL-2008-3998/BTE, GRACCIE (CSD-2007-00067) and ACI2008-0726. It is a contribution to IGCP Projects 588 and 567 and of the INQUA Focus Area on Palaeoseismicity and Active Tectonics.

References (60)

  • F. Ruiz et al.

    Late Holocene evolution of the southwestern DoñanaNacional Park (Guadalquivir estuary, SW Spain): a multivariate approach

    Paleogeography, Paleoclimatology, Paleoecology

    (2004)
  • F. Ruiz et al.

    Evidence of high-energy events in the geological records: mid-Holocene evolution of the southwestern Doñana national park (SW Spain)

    Paleogeography, Paleoclimatology, Paleoecology

    (2005)
  • P.G. Silva et al.

    Archaeoseismic record at the ancient Roman city of Baelo Claudia (Cádiz, south Spain)

    Tectonophysics

    (2005)
  • P. Terrinha et al.

    Tsunamigenic–seismogenic structures, neotectonics, sedimentary processes and slope instability on the southwest Portuguese Margin

    Marine Geology

    (2003)
  • J. Thomson et al.

    An AMS radiocarbon method to determine the emplacement time of recent deep-sea turbidites

    Sedimentary Geology

    (1994)
  • A. Udías et al.

    Seismotectonics of the Azores–Alboran region

    Tectonophysics

    (1976)
  • C. Alonso et al.

    Registro morfosedimentario de eventos históricos de alta energía en el litoral atlántico del Estrecho de Gibraltar (Trafalgar-Tarifa)

  • C. Andrade

    Tsunami generated forms in the Algarve barrier islands

    The Science of Tsunami Hazards

    (1992)
  • C. Arteaga et al.

    Presencia de materiales marinos y dunares sobre un alfar romano en la Bahía de Algeciras (Cádiz, España)

  • M.A. Baptista et al.

    Revision of the Portuguese catalog of tsunamis

    Natural Hazards and Earth System Sciences

    (2009)
  • P. Becker-Heidmann et al.

    14C dated charcoal and sediment drilling cores as first evidence of Holocene tsunamis at the Southern Spanish coast

    Radiocarbon

    (2007)
  • L.M. Cáceres et al.

    El registro geológico Holoceno como instrumento para establecer periodos de recurrencia de tsunamis: el caso de la costa de Huelva

    (2006)
  • M.L. Campos

    Tsunami hazard on the Spanish coast of the Iberian Peninsula

    The Science of Tsunami Hazards

    (1991)
  • C.J. Dabrio et al.

    The record of the tsunami produced by the 1755 Lisbon earthquake in Valdelagrana spit (Gulf of Cadiz, southern Spain)

    Geogaceta

    (1999)
  • A.G. Dawson et al.

    The diatom biostratigraphy of tsunami sediments: examples from recent and middle Holocene events

    Physics and Chemistry of the Earth

    (1996)
  • J. Galbis
    (1932)
  • J. Garcia-Orellana et al.

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

    Geophysical Research Letters

    (2006)
  • E. Gràcia et al.

    Mapping active faults offshore Portugal (36°N–38°N): implications for seismic hazard assessment along the southwest Iberian margin

    Geology

    (2003)
  • E. Gràcia et al.

    Crustal architecture and tectonic evolution of the gulf of Cadiz (SW Iberian margin) at the convergence of the Eurasian and African plates

    Tectonics

    (2003)
  • E. Gràcia et al.

    Holocene earthquake record offshore Portugal (SW Iberia): testing turbidite palaeoseismology in a slow-convergence margin

    Quaternary Science Reviews

    (2010)
  • Cited by (70)

    • The Santo André lagoon at the Atlantic coast of Portugal – Holocene evolution and event history

      2021, Palaeogeography, Palaeoclimatology, Palaeoecology
      Citation Excerpt :

      Beside these long-term processes the Portuguese coast has been exposed to short-term high energy extreme wave events that have affected the environs and humans along its shores. Special attention is given in this case to the earthquake and subsequent tsunami that devastated coastal regions of Portugal (and especially its capital Lisbon), Spain and Morocco on November 1st 1755, and has been subject to numerous studies (see tsunami catalogues for reviews: Baptista and Miranda, 2009; Kaabouben et al., 2009; Lario et al., 2011; Maramai et al., 2014). Furthermore, storms and energetic wave conditions are relatively frequent (Costa et al., 2001).

    View all citing articles on Scopus
    View full text