A new research has made it possible to date for the first time in an absolute way the lava flows of the prehistoric era of the urban area of Catania, clarifying the relationships existing between the eruptions of Etna in the Holocene Epoch (last 12,000 years) and the history of human settlements in the area at slopes of the volcano.
The studies were carried out on the lava flows of Barriera del Bosco, Larmisi and San Giovanni Galermo, located in the urban district of Catania, using paleomagnetic dating techniques. The research “Paleomagnetic dating of pre-historic lava flows from the urban district of Catania (Etna volcano, Italy)” was conducted by a team of researchers from the National Institute of Geophysics and Volcanology (INGV) in collaboration with Roma Tre University, and just published in the prestigious scientific journal ‘Geological Society of American Bulletin’. In particular, this study is the result of the collaboration between INGV researchers of the Catania and Roma2 Sections who since 2004 have been engaged in dating the historical lava flows for the geological map of Etna, published in 2011. Through these studies, researchers continued to deepen the knowledge of the eruptive activity of Etna in prehistoric ages, developing the analysis in the INGV’s Laboratory of Paleomagnetism in Rome, which is the main Italian paleomagnetic laboratory and one of the most renowned at international level.
“By comparing the paleomagnetic directions recorded by the lava flows with the geomagnetic reference models updated for the Holocene, we were able to date the Barriera del Bosco flow as the oldest of the three analyzed”, explains Stefano Branca, Director of the INGV’s Etna Observatory and co-author of the study. “Thanks to the results obtained, we were therefore able to paleomagnetically date the oldest eruptive event on Etna that reached the current urban district of Catania in the Holocene era in the time intervals between 11,234 and 10,941 and between 8,395 and 8,236 years ago”.
This study is of particular importance from the point of view of the geological reconstruction of the past of the city of Catania since, for the active volcanoes whose slopes have been inhabited since prehistoric ages, the determination of the age of historical eruptions represents a key element to investigate the relationships between eruptive phenomena and human settlements.
“During its nearly three millennia of history, Catania, the largest city located on the slopes of Mount Etna, was reached only once – in 1669 – by a large lava flow produced by an eruption in the south-eastern side of the volcano: the largest Etna lateral eruption documented in historical times”, continues Branca. “However, as we defined in the geological map of Etna, other lava flows had already reached the area of today’s urban district during Prehistory, before the foundation of the city in the Greek era, between 729 and 728 BC”.
The paleomagnetic investigations involved 12 sites distributed in the hinterland of the Sicilian city.
“The paleomagnetic directions measured in the other two lava flows analyzed, those of Larmisi and San Giovanni Galermo, coincide considering statistical uncertainties, implying that the age of emplacement is actually the same, with a statistical margin of error not exceeding 100-200 years. This, together with geological, geochemical and petrological evidence, implies that the two lava flows can be considered parts of a single large lava field that erupted in a time window between 5,494 and 5,387 years ago. This vast lava field could therefore have buried several Neolithic settlements, thus explaining the scarce presence of archaeological sites from that time found in the city of Catania”, concludes Stefano Branca.
