Fig. 1
From: Temporal gravity anomalies observed in the Tokai area and a possible relationship with slow slips
The gravity observation sites and the raw data. a The study area. b The locations of the gravity observation sites. OMZ denotes the crustal deformation monitoring station of the GSI, and KKG and TYH are those of Nagoya University. The gray and red contours represent the long-term slow slips which occurred during 2001–2006 and 2013–2017, respectively [Ozawa et al. 2016; the Geospatial Information Authority of Japan (GSI) (2017)]. The blue circle denotes the asperity of the anticipated great earthquake. Along the thick green line, the presence of high-pressure fluids is suggested (Kato et al. 2010). c The observed gravity changes (g0) obtained after standard corrections of tides, polar motion and the barometric effect. The vertical axes denote relative gravity change in μGal and offsets are added for visualization. The different colors denote different S/Ns of the instruments. The error bars denote measurement errors (1σ)