Italy's biggest lake hides a fault line and a drowned Roman-era town
Lake Garda looks serene, but it sits in one of Italy's most earthquake-prone zones. Around the year 243 a quake apparently triggered a landslide and flood that wiped out the town of Benaco. Since then tremors have toppled houses, sunk a mountain near Salò and split Malcesine's square with a 200-metre crack.
Garda is the largest lake in Italy, wedged between Brescia and Milan on one side and Verona and Venice on the other. Its northern end pushes into the Alps among the Garda Mountains and the Brenta Group, while the southern end spreads over the upper Po plain. Three jurisdictions share the shore: Brescia to the south-west, Verona to the south-east and Trentino to the north.
Both of its names tell stories. The Romans called it Benacus and some worshipped it as a god linked with Neptune; that older word is probably Celtic, perhaps meaning horned, a nod to its many promontories. Garda itself is Germanic, from warda, a place of watching or safety, and a cluster of similar place names records Lombard settlement between the 6th and 8th centuries.
Ice gave the lake its shape. A Paleolithic glacier carved the typical moraine valley, though geologists now suspect it filled a hollow already cut by rivers 5 to 6 million years ago. South of the water, successive glaciations piled up a morainic amphitheatre of gentle hills that seem to cradle the lake. The Sarca is the main river feeding it, the Mincio at Peschiera is its only exit, and when the Adige runs dangerously high its surplus is sent through the Mori-Torbole tunnel into Garda. A submerged fault between Sirmione and Punta San Vigilio partly separates the waters of the two halves.
The catchment is unusually small for such a lake: the water stretches 52 kilometres, the basin only 95, with peaks such as Presanella and Adamello rising above 3,500 metres. The seismic record runs from Benaco's loss through quakes in 793, 1457, 1703, 1810 and 1836, the last setting off landslides on Mount Tomè that released a violent burst of water.
Source: Lake Garda
