An interpretation of SPring-8 ground elevation by the empirical ATL-law approach

Starting in 1996, the coordinates of the accelerator components on the SPring-8 storage ring were continuously surveyed for over two decades. The dispersion of the elevation changes of the ground motion $⟨d{z}^2⟩$ analyzed from the aspect of the empirical $ATL$-law which has been intensively researched since 1990s. With the $ATL$-law, $⟨d{z}^2⟩$ can be expressed as products of a ground diffusion coefficient $A$, temporal survey spans $T$, and spatial scales $L$. The coefficient $A$ is well known to depend on the local geology and is evaluated as $(7.6\pm 1.4)\times {10}^{-6}$ μm${}^2$/s/m for the SPring-8 storage ring. In this paper, a transition of survey methods in the SPring-8 storage ring is reviewd and survey results both in horizontal and vertical directions are presented. Furthermore, the relevance of the $ATL$-law approach for the ground elevation dispersion are discussed.