Fig. 9

Cracks appeared on a training wall near the no. 39 SPW in Owakudani. White arrows indicate the positions where cracks were formed. a On May 27, no apparent cracks had formed. b Three weeks later, cracks A and B with sulfur and ferrioxide at the opening had formed. c From crack A, water seems to be seeping out but the place where crack C will be formed seems intact. d A week later, crack C is newly formed. The size of the stone blocks paving the wall is 40 cm × 30 cm. The location of these cracks is shown in Fig. 2. All photographs are taken by HSRI