Typhoons were devastating in their immediate effects and also played an indirect role by exacerbating problems which we have already mentioned, notably differential settlement and corrosion. The direct destruction caused by typhoons was enormous and they were a great menace to the inhabitants. There remain a lot of records and photographs. Man-sized stones and mine pillars, torn from the retaining wall along the shore, were hurled by breakers against the buildings and broke thick concrete walls and roofs. Once a tree-storied reinforced concrete building was totally destroyed. Needless to say, such light elements as wooden fittings and the roof drains were terribly damaged. While there were people living on the island, this kind of damage was repaired as soon as possible, but after the mine was closed and the island deserted, no repair was done and the weathering was much accelerated. This process is clearly seen in the wooden roofs with galvanised steel sheets, which were used for the shrine, the temple ('Sempuku-ji'), the cinema, building No. 6, the gymnasium, and so on. The roof trusses of the cinema and gymnasium were made of steel but there sheathing roof boards were made of wood. Thyphoon wind pressure caused rainwater to enter through galvanised sheets which had been rusted and weakened, then the sheathing roof boards were peeled off and the beams were tottering as a result of rotting at the joints. 5 or 6 years after the mine closed, the eaves fell down and within 8 to 10 years the entire roof and its supporting beams had collapsed. This had nothing to do with the fact that there were timber structures for the roof and frames and the roof trusses of the clubhouse and the priest's lodging, the roofs of which were tiled with 'hongawara' (a Japanese tiling system with alternating flat tiles and semi-circular cover tiles) are scarcely damaged, although the interior parts of these buildings are damaged because of loss of fittings at the openings. Essentially it was salt corrosion that damaged them and judging from their condition we can say that timber construction is more durable than reinforced concrete if it is well waterproofed.