An international team of researchers has found that medieval deforestation caused two destructive tsunamis on Lake Iseo in northern Italy, infohub.kz reports.
The findings were published in the scientific journal Nature Communications. The specialists combined seismic profiles, sediment cores, archaeological finds and historical documents, including a 12th-century manuscript from the Vatican Library. Using computer modeling, the authors established that human-driven landscape changes turned moderate earthquakes into sources of deadly waves.
Before the fall of the Roman Empire, the Oglio River delta was covered in dense forests whose root systems held the soil firmly in place. The underwater slopes remained gentle and descended smoothly to the lake's maximum depth of 250 meters. Later, intensive clearing of land for pastures and mining led to a threefold increase in sediment washed into the lake. The accumulated deposits made the underwater shores extremely steep and unstable.
When the 1117 Verona earthquake struck, the overloaded slopes collapsed into the water. The underwater landslide generated a giant tsunami with waves more than 50 meters high in the northern part of the lake, flooding land 2.7 kilometers inland. A second disaster followed the 1222 Brescia earthquake, when waves reached 13 meters. Monte Isola island absorbed part of the impact, but towns were still inundated.
The researchers warn that eight centuries of renewed erosion and dense coastal development create a colossal risk of a repeat catastrophe. Human activity triggered underwater landslides and giant tsunamis on Lake Iseo in the 12th–13th centuries, and modern shoreline development could repeat the tragedy, the physicists warned, ScienceAlert writes.