How Human Activity Influences Massive Waves in Lake Iseo
A recent study published in Nature Communications explores the connection between human impact, underwater landslides, and the formation of enormous waves in alpine freshwater lakes, focusing on Lake Iseo. This lake was the site of a significant earthquake on January 3, 1117, which triggered a massive underwater landslide and generated a destructive tsunami. Researchers are analyzing both the historical event and the potential for similar catastrophes to occur in the present day.
Back in 1117, northern Italy experienced a powerful earthquake, documented in an ancient manuscript preserved in the Vatican Library. The quake caused lake waters to rise dramatically, leaving few survivors in nearby villages. For centuries, local communities had cleared forests and grazed livestock on the slopes of the Val Camonica valley, a practice dating back to Roman times. This deforestation exposed the slopes to erosion, leading to increased runoff where the Oglio River began depositing three times more sediment—mud and sand—into Lake Iseo.
Present-Day Threats and Potential Disasters
Today, a vast underwater delta with a volume of 62 million cubic meters has formed at the northern end of Lake Iseo. The earthquake of 1117 caused this sediment to slide along the lakebed for 10 kilometers, displacing a massive volume of water. French and Swiss physicists recreated this event using computer simulations, revealing a wave over 5 kilometers long that accelerated to speeds of 180 km/h at a depth of 250 meters. The wave’s height reached up to 50 meters on the nearest shore, flooding the plains nearly 3 kilometers inland. The island of Monte Isola, located in the middle of Lake Iseo, helped reduce the wave’s height to 5 meters in some areas.
Another earthquake on December 25, 1222, also generated waves as high as 13 meters in Lake Iseo. Over the past 800 years, the river has continued to deposit millions of tons of sediment onto the lake’s underwater slopes. Nowadays, the shores of Lake Iseo are densely populated resort areas, which significantly raises the stakes for potential disasters. Should the underwater sediment wall collapse again due to an earthquake, floodwaters could reach the town of Pisogne within 10 seconds and Lovere within 25 seconds. Notably, emergency warning systems would be unable to activate sirens in time to alert residents.
The study emphasizes the critical need to understand past natural disasters in order to mitigate current risks.
Source: Nature Communications
As human development continues near natural bodies of water, the likelihood of repeating such catastrophic events grows. It is therefore essential to consider both environmental and geological factors in urban planning and infrastructure development around lakes like Iseo. The insights from this research provide a foundation for improving safety measures and emergency preparedness in the region.