The two major faults that rip Kumamoto are the Hinagu fault, which runs from Yatsushiro to Mifune, and the Kitagawa fault, which runs along the north-eastern side of the Uto peninsula up to Aso. The latter is interesting: it is a strike-slip zone in the city but becomes a rift zone as it nears Aso. This has resulted in Tateno gap, through which the water of Aso flows - without this gap, the Aso caldera would be a large lake. Route 57 threaded this gap until it was destroyed by erosion. Rather than rebuilding on the original route, a tunnel was built between Ozu and Akamizu, which opened the other day. I’d driven the road over the caldera lip, which has more hairpins than a harlot, so the new road should save time and energy and likely revitalize the areas in eastern Aso. - William