Investigation Report on Lightning Damage on Inuyama Castle and Related Lightning Impulse Voltage and Current Test of Tile

There was a lightning strike on a tile that depicted the shape of a mythical fish with a lion-like head on the top of the castle tower of Inuyama Castle, a National Treasure (Aichi Prefecture), damaging a portion of the tail and fins of the fish, and scattering broken pieces of the tile. The authors performed a site investigation on July 28, 2017. Furthermore, we carried out a lightning impulse voltage and current test on a tile by using an impulse high-voltage generator and impulse large-current generator. In this report, we clarified the danger of lightning strikes to important cultural properties.