Landslide clusters in the Tovel Valley (Brenta Dolomites, N Italy) triggered by far field earthquakes?

Large blocky landslide deposits are widespread in Alpine valleys of northern Italy, yet their timing, emplacement history, and geomorphic significance remain debated. In the Tovel Valley (Brenta Dolomites, Italy), extensive blocky accumulations have been variously attributed to deglaciation or to younger slope-failure events, with important implications for valley evolution and hazard assessment. This study aims to determine the timing, sequence, and emplacement relationships of the main deposits, evaluate their role in valley damming and the evolution of Lake Tovel, and assess long-term drivers and short-term triggers within a regional Alpine context. We combine detailed geomorphological mapping with analysis of LiDAR-derived topography and orthophotos, supported by cosmogenic 36Cl exposure dating of boulders from six deposits. Exposure ages indicate Holocene emplacement and suggest two broad periods of landslide activity. The older phase is represented by a principal Mid-Holocene age population centred at 5.21 ± 0.16 ka, together with overlapping chronological constraints from other deposits, whereas younger exposure ages fall between ∼1.0 and ∼0.6 ka. Integration of exposure ages with superposition relationships, morphology, lithology, and inferred source areas allows reconstruction of a relative landslide sequence involving repeated independent failures from both valley flanks. The distribution and volumes of the deposits suggest that several events were capable of partially or fully damming the valley, consistent with a multi-phase history including lake formation, drainage reorganization, and renewed damming at Lake Tovel. The landslides reflect persistent long-term predisposing factors, including carbonate lithology affected by karst dissolution, inherited structural anisotropies, and glacial and paraglacial modification, while temporal clustering suggests episodic short-term triggering during periods of heightened susceptibility. Seismic shaking is considered the most plausible regional-scale trigger for the younger cluster, whereas trigger attribution for older events remains uncertain. Overall, the Tovel Valley provides an illustrative case study of Holocene large landslides in an Alpine carbonate setting, highlighting the value of integrating geomorphic analysis with cosmogenic dating to resolve landslide sequences and valley evolution.