Isn't Italy a little geologically unstable?
I'd be a bit nervous, going through a long tunnel, in a region known for vulcanism and earthquakes.
Tunnels are actually pretty safe in earthquakes, Japan for example is criss crossed with them.
A tunnel is actually the least likely to shake; if you shake a jello with fruit inside it, the surface moves a lot but the interior fruit won’t move all that much.
The 57 km Gotthard Base Tunnel has been in operation since 2016. There's also a 3km long tunnel between France and Italy that opened in 1882. Nowadays there's probably hundreds of 1km+ tunnels in the Alps.
Italy isn't a puny country, it's over 1000kms between Sicily and the Alps (Like LA to Albuquerque), seems the fault lines reaches northern Italy (about 100km from the alps) but the amount of larger quakes seems smaller there.
It is unstable, but (I think) more so in the south. I'm not sure that the Alps region is unstable.
Let me introduce you to the Seikan Tunnel [1] between the islands of Honshu and Hokkaido in Japan, 53.85km with 23.3km of that under the sea.
[1] https://en.wikipedia.org/wiki/Seikan_Tunnel