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

Gràcia, Eulália; Vizcaino, Alexis; Escutia, Carlota; Asioli, Alessandra; Rodés, Ángel; Pallàs, Raimón; García-Orellana, Jordi; Lebreiro, Susana Martin; Goldfinger, Chris

doi:10.1016/j.quascirev.2010.01.010

Cited by 144 publications

(147 citation statements)

References 63 publications

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“…3900-3600 cal BP and ca.2200-2000 cal BP ( Fig. 2), consistent with the off-shore record of earthquake related turbidite deposits (Gracia et al, 2010). One of these events is historically documented and noted in the existing seismic and tsunami catalogues for Spain (i.e.…”

Section: Conclusion: On-shore Catalogue Of Palaeotsunami and Recurresupporting

confidence: 82%

“…Data such as increased magnetic susceptibility suggest the occurrence of an intervening tsunami event, but this is not validated by other complementary data on-shore. This event has an age of ca.7000-6S00 cal BP, and can be reasonably corre lated in age to the ES-turbidite event (Gracia et al, 2010), Therefore, a tsunamigenic origin for the on-shore deposits is possible.…”

Section: Record Of Ewe On-shorementioning

confidence: 71%

“…In addition, there is no record of widespread turbidite deposits generated by a strong earthquake of this age (Gracia et al, 2010). Local earthquake-related turbidite deposits have been reported by Vizcaino et al (2006) at ca.3600 cal BP.…”

Section: Record Of Ewe On-shorementioning

confidence: 90%

“…A common conclusion is that, as such deposits indicate only the occurrence of a high energy event, the marine origin of the event, and the inundation of coastal areas by sea water, they can only be referred to as extreme wave events or EWE (Kortekaas, 2002;Kortekaas and Dawson, 2007;Bridge, 200S;laffe et al, 200S;Switzer, 200S;Switzer and lones, 200S;Lario et al, 2010). The record of earthquake-triggered turbidites off-shore in this area (Gracia 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).…”

Section: Record Of Ewe On-shorementioning

confidence: 98%

“…For instance, the events reported between 245 and 209 BC were compiled from diverse sources (Moreira de Mendo<;:a, 175S) and may well correspond to the same event, assigned erroneously to different ages in separate localities. It must be also considered that, although Galbis The well-documented 1755 Lisbon tsunami-earthquake is clearly associated with the E3-turbidite in the off-shore record (Gracia et al, 2010). This recent EWE has an abundant historical written record for more than 30 sites along the south-western Spanish shores, complemented by extensive analyses of its geological effects on the Gulf of Cadiz area (Campos, 1991;Dabrio et al, 1999;Martinez Solares, 2001;Luque et al, 2001Luque et al, , 2004Luque, 2002;Morales et al, 200S;Lario et al, 2010).…”

Section: The Largest Record Of Ewe Deposits Recorded Along the Gulf Ofmentioning

confidence: 99%

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Holocene palaeotsunami catalogue of SW Iberia

Lario

Cardeña

Goy

et al. 2011

Quaternary International

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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 geomor phological 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 palae oearthquakes 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.

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Section: Conclusion: On-shore Catalogue Of Palaeotsunami and Recurresupporting

confidence: 82%

Section: Record Of Ewe On-shorementioning

confidence: 71%

Section: Record Of Ewe On-shorementioning

confidence: 90%

Section: Record Of Ewe On-shorementioning

confidence: 98%

Section: The Largest Record Of Ewe Deposits Recorded Along the Gulf Ofmentioning

confidence: 99%

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Holocene palaeotsunami catalogue of SW Iberia

Lario

Cardeña

Goy

et al. 2011

Quaternary International

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Seismic and gravity constraints on the nature of the basement in the Africa‐Eurasia plate boundary: New insights for the geodynamic evolution of the SW Iberian margin

et al. 2014

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We present a new classification of geological domains at the Africa-Eurasia plate boundary off SW Iberia, together with a regional geodynamic reconstruction spanning from the Mesozoic extension to the Neogene-to-present-day convergence. It is based on seismic velocity and density models along a new transect running from the Horseshoe to the Seine abyssal plains, which is combined with previously available geophysical models from the region. The basement velocity structure at the Seine Abyssal Plain indicates the presence of a highly heterogeneous, thin oceanic crust with local high-velocity anomalies possibly representing zones related to the presence of ultramafic rocks. The integration of this model with previous ones reveals the presence of three oceanic domains offshore SW Iberia: (1) the Seine Abyssal Plain domain, generated during the first stages of slow seafloor spreading in the NE Central Atlantic (Early Jurassic); (2) the Gulf of Cadiz domain, made of oceanic crust generated in the Alpine-Tethys spreading system between Iberia and Africa, which was coeval with the formation of the Seine Abyssal Plain domain and lasted up to the North Atlantic continental breakup (Late Jurassic); and (3) the Gorringe Bank domain, made of exhumed mantle rocks, which formed during the first stages of North Atlantic opening. Our models suggest that the Seine Abyssal Plain and Gulf of Cadiz domains are separated by the Lineament South strike-slip fault, whereas the Gulf of Cadiz and Gorringe Bank domains appear to be limited by a deep thrust fault located at the center of the Horseshoe Abyssal Plain.

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Lacustrine turbidites as a tool for quantitative earthquake reconstruction: New evidence for a variable rupture mode in south central Chile

et al. 2014

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Understanding the long-term earthquake recurrence pattern at subduction zones requires continuous paleoseismic records with excellent temporal and spatial resolution and stable threshold conditions. South central Chilean lakes are typically characterized by laminated sediments providing a quasi-annual resolution. Our sedimentary data show that lacustrine turbidite sequences accurately reflect the historical record of large interplate earthquakes (among others the 2010 and 1960 events). Furthermore, we found that a turbidite's spatial extent and thickness are a function of the local seismic intensity and can be used for reconstructing paleo-intensities. Consequently, our multilake turbidite record aids in pinpointing magnitudes, rupture locations, and extent of past subduction earthquakes in south central Chile. Comparison of the lacustrine turbidite records with historical reports, a paleotsunami/subsidence record, and a marine megaturbidite record demonstrates that the Valdivia Segment is characterized by a variable rupture mode over the last 900 years including (i) full ruptures (M w~9 .5: 1960, 1575, 1319 ± 9, 1127 ± 44), (ii) ruptures covering half of the Valdivia Segment (M w~9 : 1837), and (iii) partial ruptures of much smaller coseismic slip and extent (M w~7 .5-8: 1737, 1466 ± 4). Also, distant or smaller local earthquakes can leave a specific sedimentary imprint which may resolve subtle differences in seismic intensity values. For instance, the 2010 event at the Maule Segment produced higher seismic intensities toward southeastern localities compared to previous megathrust ruptures of similar size and extent near Concepciόn.

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

Cited by 144 publications

References 63 publications

Holocene palaeotsunami catalogue of SW Iberia

Holocene palaeotsunami catalogue of SW Iberia

Seismic and gravity constraints on the nature of the basement in the Africa‐Eurasia plate boundary: New insights for the geodynamic evolution of the SW Iberian margin

Lacustrine turbidites as a tool for quantitative earthquake reconstruction: New evidence for a variable rupture mode in south central Chile

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