Marine tephrochronology at Stromboli volcano: reconstruction of flank collapses and tsunami hazards over the last 10,000 years

Over the last two decades, tephrochronology has become a fundamental tool for high-resolution stratigraphy, providing constraints for dating, correlation, and synchronization applicable to various Earth sciences disciplines. In coastal and island volcanic settings, the analysis of the texture, mineralogy, and geochemistry of volcanic particles allows the identification of the source volcanoes and the reconstruction of eruptive histories, also providing crucial information on associated hazards, such as slope collapse and tsunamis.

In this study, we applied an integrated tephrochronological, sedimentological, and geochemical approach to three marine sediment cores collected ~30–43 km northwest of Stromboli volcano (southern Tyrrhenian Sea). Marine sedimentary sequences are particularly valuable in this context because they preserve both turbidite sequences produced by past volcanic flank collapses and tephra deposits from nearby volcanoes, providing essential chronological constraints. The cores consist of epiclastic sediments and hemipelagic muds intercalated with volcaniclastic deposits, which were divided into three main types: (a) primary tephra (and cryptotephra) layers, representing direct fallout deposits from explosive eruptions; (b) mono-magmatic volcaniclastic turbidites that were directly linked to collapse events of the north flank of Stromboli; (c) multi-magmatic volcaniclastic turbidites resulting from the mixing of materials from multiple volcanic sources during transport through the Stromboli channel. We focused on the upper 2 m of the cores, representing the Holocene period, where sedimentological and geochemical analysis allowed the identification of three primary tephra layers, which could be correlated with well-known eruptions on land. These include the Vallone Gabellotto rhyolitic tephra (~9–8.7 ka) at the base of the investigated sections and which constrains the record to the last ~10 kyr, a high-K trachyandesitic tephra related to Neostromboli explosive activity (~8.7–6 ka), and the Monte Pilato rhyolitic tephra (~1.2 ka BP) near the top of the cores. Together, these markers provide a solid time frame for constraining the ages of the intercalated volcaniclastic deposits. Within this framework, at least 8 mono-magmatic volcaniclastic turbidites were identified that are geochemically correlated with the main eruptive periods of Stromboli. Due to their homogeneous compositions, we interpreted these turbidites as genetically related to collapse events at the flank of Stromboli, implying that at least 8 large-scale landslide events have occurred at Stromboli during the Holocene. Compared with the 2002 tsunamigenic landslide (~30 × 10⁶ m³), the landslide volumes estimated from the turbidite thicknesses (~45 × 10⁶ to ~58.5 × 10⁷ m³) suggest that all were of higher magnitude and potentially tsunamigenic.

This study highlights how marine tephrochronology represents an effective tool to reconstruct volcanic events and associated risks, providing crucial data for hazard assessment and mitigation strategy development in the southern Tyrrhenian Sea.