Tsunami boulders in Majorca Island (Balearic Islands, Spain)
2019
Roig-Munar, Francesc Xavier | Rodríguez-Perea, Antonio | Vilaplana, Joan Manuel | Martín-Prieto, José Angel | Gelabert Ferrer, Bernadí
Large boulders have been found on marine cliffs from 22 study sites on Majorca, in the Balearic Islands (Western Mediterranean). These large imbricated boulders of up to 25 t are located on platforms that form the rocky coastline of Majorca, several tens of meters from the edge of the cliff, up to 15 m above sea level and kilometers away from any inland escarpment. They are located on the east and south coasts of Majorca, where wave height and energy are low compared with those from the N and NE. Further, the boulders are located in the exact places where numerical models of tsunami simulation from submarine earthquakes on the North African coast predict tsunami impact on Majorca. Documentary sources also confirm a very large tsunami affecting the SE coast of Majorca in 1756, with a run-in up to 2 km and a run-up up to 45 m. According to radiocarbon data and rate of growth of dissolution pans, the ages of the boulders of the studied localities range between 1591 CE and 1894 CE, although most of them are concentrated around the year 1790 CE. Although some storm waves might play a role in their dislodging, the distribution of the boulder sites along the island, the degree and direction of imbrication and the run-up necessary for their placement suggest transport from northern African tsunami waves that hit the coastline of Majorca.
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