Human land use primed Lake Iseo's delta to collapse and unleash tsunamis

Human-enhanced tsunami hazard in large lakes

Centuries of deforestation, farming, and grazing in Italy's Val Camonica tripled sediment flowing into Lake Iseo, steepening the Oglio River Delta until it collapsed during the 1117 and 1222 CE earthquakes. Combining sediment cores, seismic surveys, and numerical modeling, researchers reconstruct these medieval collapses—one leaving a deposit roughly 7 meters thick and some 62 million cubic meters in volume—and show they could have spawned destructive lake tsunamis. The work argues that tsunami hazard assessments in populated, seismically active lake basins must account for human-driven sediment loading.