Kirk had written about destruction of the basalt columns near Tateno by construction workers intent on stabilizing the gorge - ironic, since those columns, having been there for some 300,000 years, were not likely going anywhere. While construction workers being unaware of the geologic value of a cliff is understandable, that their superiors didn’t realize this is inexcusable. Perhaps some disaster mitigation is possible.
Aso underwent four eruptions from 300,000 to 90,000 years ago; earlier eruptions led to creeping, slowly-cooling basalt that crystallized into hexagonal-shaped columns, while the last ejected an amount of material equivalent to the volume of Mt. Fuji which covered half of Kyushu and resulted in the caldera that we know today. (Still want to live in Tokyo, knowing that?)
Takachiho gorge displays basalt columns from the earlier eruptions topped by tuff deposited when Aso went complete kablooey in its grand finale 90,000 years ago; the two rock types are clearly seen in the below photo. Takachiho has made the list of the 11 most beautiful basalt columns in the world. See the article below for more info and beautiful photos. - William
P.S. - I know of a stunning location of crystallized basalt that plunges into the sea down in southern Kagoshima and is accessible to the slightly adventurous. If interested, PM me.
https://www.fromthegrapevine.com/nature/11-intriguing-basalt-formations-around-world