High-resolution SH wave exploration to assess damage to the Sakuradani Kofun Tumulus No.2 caused by the Noto earthquake
High-resolution SH wave exploration to assess damage to the Sakuradani Kofun Tumulus No.2 caused by the Noto earthquake
Kofun, ancient Japanese burial mounds, are representing sophisticated geotechnical structures from ancient Japan. However, archaeological investigations of these heritage sites are often strictly restricted. Following the 2024 Noto Peninsula Earthquake, damage was observed in the Sakuradani Kofun Tumuli, including a subsidence (approx. 1.2 m diameter, 6.4 m length at 34.7° slope) confirmed in Tumulus No. 2. To aid restoration planning, this study assesses the subsurface damage in Tumulus No. 2 using non-invasive methods. Given the depth limitations of Ground Penetrating Radar (GPR), a Shear-Wave (SH-wave) reflection survey was selected to investigate the internal structure, focusing on the delineation of potential cavities and loose zones associated with the subsidence. A custom low-power vibratory source was utilized to minimize physical impact on the mound, employing waveform stacking to secure sufficient signal quality. The obtained seismic reflection profiles, interpreted alongside Dynamic Cone Penetration Test (DCPT) data, indicated reflectors corresponding to the dense foundation layer. Furthermore, hyperbolic reflections and amplitude attenuation were observed, which appear consistent with the presence of subsurface voids and associated loosened areas. These findings suggest that SH-wave reflection surveys can be an effective approach for the high-resolution, non-destructive assessment of structural damage in earthen heritage sites.
Yutaro Hara; R. Kuwano
4th International Symposium on the Preservation of Monuments and Historic Sites
Materials, Monitoring and Geotechnical Investigation Methods
https://doi.org/10.53243/tc301-2026-88