Landslides on volcanic islands are dangerous geological phenomena, capable of generating tsunamis that can spread far from their sources ... the last one to come to mind is the one that recently hit Anak Krakatau.
A study published in Scientific reports investigated the collapse of the north-west flank of Stromboli in the Aeolian Islands; between 1343 and 1456, they were the cause of tsunami that reached the coast of Campania.
This interdisciplinary work is linked to volcanological and archaeological skills on the ground.
(the National Institute of Geophysics and Volcanology (INGV), the Department of Earth Sciences of the University of Pisa, the Italian Universities of Modena-Reggio Emilia and Urbino, the National Research Council (CNR), the City University and the American Numismatic Society of New York.)
(A) General map of Stromboli showing the studied area in the red zone. The inset shows the location of Stromboli in the Tyrrhenian Sea. (B) Aerial view, from north to south, of Stromboli (Google Earth image), showing the location of the trenches and the archaeological site of San Vincenzo. - Doc. references in sources
It was known that Stromboli was capable of producing small tsunami, as in December 2002, but the study shows its ability to produce much larger tsunamis that can reach very distant coasts.
The oldest event of greater magnitude took place in 1343: responsible for the rapid abandonment of the island, this tsunami is linked with the destruction of the ports of Naples and Amalfi.
It is narrated by Francesco Petrarca (Petrarch 1304-1374), Florentin poet and humanist, on an embassy mission of Pope Clement VI to Naples, and who as a witness, reported the episode in a letter, where he describes a violent sea storm on 25 November 1343 ... attributed today to the arrival of several waves of a tsunami generated by a landslide on Stromboli.
Following an intense eruptive activity and collapse, the island was abandoned in the first half of the 14th century, until the end of the 16th century, despite its important role in trade in the Mediterranean sea.
Stromboli - the sequence of tephra and tsunami in trench 3 - The T2 consists of two beds of red and black lapilli terebris and an ocher-colored bed, linked to the tephra deposit resulting from an explosive activity at the craters at the top, as well as dust fallout from a landslide. - T1 is a fine ash deposit, prior to the tsunami - Upper Tsunami (Utd); Intermediate sandy bed (Itd); Lowermost bed (Ltd) - The red arrow indicates a ceramic tile. - Doc. references in sources
This study, essentially scientific, has no immediate implications.
It first reveals the impact of repeated adverse natural events on a small human community, and its inability to overcome the additional effects of earthquakes and coastal tsunamis.
On the other hand, it points to a higher than expected exposure risk of tsunami for people living near the southern coast of the Tyrrhenian Sea (Campania, Calabria and Sicily).
The discovery of three catastrophic collapses of the Sciara del Fuoco, during a relatively recent and short period, indicates an underestimated danger so far.
The frequency of collapse of the flank of Stromboli, the maximum volume of these, and that of a volcanic eruption on a large scale, all these parameters must be studied to assess the hazards at the regional scale.
Source: Nature Scientific Reports - Geoarchaeological evidence of Middle-age tsunamis at Stromboli and consequences for the tsunami hazardin the southern Tyrrhenian sea - by M. Rosi & al. - under a Creative Commons Attribution 4.0 International License