The Lisbon earthquake of 1755 is only the latest example of a long chain of destructive tsunamis affecting SW Iberia and NW Africa, which seem now to be recurrent with a approximate regularity of ~700 years for 8 Mw events and ~3500 years for larger 8.7 Mw ones. Those are the conclusions of a geological study in the coast of Cádiz Province (Andalusia) focused on describing one that left a clear mark in the coastal sediment some 4200 years ago.
Benjamin Koster & Klaus Reicherter. Sedimentological and geophysical properties of a ca. 4000 year old tsunami deposit in southern Spain. Sedimentology 2015. Pay per view → LINK [doi:10.1016/j.sedgeo.2014.09.006]
Paper freely available at Researchgate anyhow.
The coastlines around the Gulf of Cádiz were affected by numerous tsunami events damaging infrastructure and causing countless human losses. A tsunami deposit at Barbate–Zahara de los Atunes, Spain, is located at various heights above mean sea level and shows several characteristics indicative of high-energy event deposition. This study uses sedimentology, foraminifera assemblage, magnetic susceptibility, X-ray fluorescence analysis, ground penetrating radar (GPR) to support an interpretation of high-energy deposition and determine the deposit's transport mechanisms and sediment source. Radiocarbon and optically stimulated luminescence dating of the tsunami deposit reveals ages of ~ 4000 BP and does not support the AD 1755 Lisbon event as suggested in former publications.
I fin this particularly interesting because the city that was for some 1500 years the main one of Atlantic Europe, central in both Megalithism and Bell Beaker, the so-called Castro do Zambujal (Torres Vedras, Portugal), was abandoned c. 1100 BCE after the canal of 10 km. that linked it to the ocean was silted, maybe by one of these devastating tsunamis.
This event, as well as many other details (length of the canal, geographical location beyond The Pillars, Mycenean Greek influence in presumably rival El Argar civilization, number of princely tombs, extension of Megalithism to "Lybia and Tyrsenia"...) fit strangely too well with the narration of Plato about Atlantis, which would then have happened just some 900 years (and not 9000) before his life. With less detail, the Mycenaean presence in Iberia would also correspond well with two of the mythical works of Herakles (Hercules): the conflict with Geryones and the stealing of the Hesperian apples by cheating Atlas. The early Greeks, whose influence in El Argar B is very apparent in the adoption of pithos (jar) burial, would have gone there largely in search of tin, the strategical mineral of the Bronze Age, which was only found in abundance in NW Iberia (and Cornwall but that source was exploited only later, it seems).