Revision of the Portuguese catalog of tsunamis

Abstract

Abstract. Catastrophic tsunamis are described in historical sources for all regions around the Gulf of Cadiz, at least since 60 BC. Most of the known events are associated with moderate to large earthquakes and among them the better studied is 1 November 1755. We present here a review of the events which effects, on the coasts of the Portuguese mainland and Madeira Island, are well described in historical documents or have been measured by tide gauges since the installation of these instruments. For a few we include new relevant information for the assessment of the tsunami generation or effects, and we discard events that are included in existing compilations but are not supported by quality historical sources or instrumental records. We quote the most relevant quantitative descriptions of tsunami effects on the Portuguese coast, including in all pertinent cases a critical review of the coeval sources, to establish a homogenous event list. When available, instrumental information is presented. We complement all this information with a summary of the conclusions established by paleo-tsunami research.

New study on the 1941 Gloria Fault earthquake and tsunami

“…1) recorded the tsunami. Ponta Delgada tide station, in the Azores, recorded a maximum amplitude of 0.2 m. The Portuguese press reported tsunami observations close to Lisbon and the overtopping of shallow areas close to Oporto (Leixões) (see Baptista and Miranda (2009) for details). Haslett and Bryant (2008) described tsunami observations along the English Channel at Newlyn (Cornwall, United Kingdom) and Le Havre (France).…”

“…Among these events are those that occurred on 25 November 1941 (Udias et al, 1976;Lynnes and Ruff, 1985), 9 June 1969 (Argus et al, 1989), 26 May 1975(Buforn et al, 1998Argus et al, 1989;Kaabouben et al, 2008) and 17 October 1983 (Argus et al, 1989). Some of these earthquakes generated tsunamis, described in historical documents and recorded by tide stations, namely on 31 March 1761, 25 November 1941and 26 May 1975(Baptista et al, 2006Kaabouben et al, 2008;Baptista and Miranda, 2009).…”

Earthquakes and tsunami in November 1755 in Morocco: a different reading of contemporaneous documentary sources

“…The tsunami caused by the Great Lisbon Earthquake, on the morning of 1 November 1755, remains the only destructive event described in some detail by historic documents, though an earlier event known to have occurred in Lisbon on 26 January 1531 (Baptista and Miranda, 2009), was mentioned in journals in 1756, both in France and in England (JHMT, 1756a;Wolsall, 1756, footnote).…”

Impact of a tsunami generated at the Lesser Antilles subduction zone on the Northern Atlantic Ocean coastlines

“…The Atlantic Ocean, a low rate expanding ocean (the average spreading rate of the mid-ocean ridge is estimated around 2.5 cm yr −1 ), is not bordered by a fire belt like the Pacific Ocean, but shows however some particular places to monitor and able to trigger some catastrophic tsunamis according to available tsunami databases (Gusiakov and Mercado, 2002;Lander et al, 2002;Baptista and Miranda, 2009;Baptista et al, 2011;NGDC, 2013) and geological settings. These tsunami generating zones are split in two parts: in one hand, the active zones, represented by convergent plate boundaries: the Antilles subduction zone for the western side of the Atlantic, which generated several local or regional tsunamis as for example the 1867 Virgin Islands event (Zahibo et al, 2003;Barkan and ten Brink, 2010), and the Iberian Peninsula fault system for the eastern side, especially known because of the 1755 "Lisbon" tsunami, which was historically recorded at lots of locations in the Northern Atlantic Ocean including the Lesser Antilles (Barkan et al, 2009;Roger et al, 2010a, b, c).…”