Fig. 4

Regional and tectonic stress patterns around Mt. Ontake. a Regional stress pattern inferred from focal mechanism solutions for May 2012 to July 2014 (Terakawa et al. 2016). b Tectonic stress pattern for the Ontake region (Terakawa and Matsu’ura 2010). The color scales in a, b denote the AVITP (“Estimation errors of the regional stress field around Mt. Ontake” section), which was used as the estimation error of the stress field. The gray open circles in a, b indicate the data that were used to infer the regional and tectonic stress fields, respectively. c Closeness of the regional and tectonic stress patterns measured with the inner tensor product between the two tensors. The black open circles denote the data used to estimate the pore-fluid pressures in “FMT analysis around Mt. Ontake” section. The dashed rectangle in red represents the region A, where the two stress patterns in a, b significantly differed