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Table 1 The characteristics of b-values, LFEs, and SSEs activities in each region

From: Stress state along the western Nankai Trough subduction zone inferred from b-values, long-term slow-slip events, and low-frequency earthquakes

RegionLFE activitySSE activity—sizeb-value
Kii Peninsula×High (b ~ 1.2)
Kii Channel×〇 (but, not during the analysis period)—Medium (Mw 6.6–6.7)Moderate (b ~ 1.0)
Central Shikoku〇 Very small (Mw 6.0–6.3)Low (b ~ 0.6)
Western Shikoku〇 Small (Mw 6.0–6.3)High (b ~ 1.2)
Bungo Channel〇 Large (Mw 7.0–7.1)High (b ~ 1.2)
Northern Miyazaki×〇 (but, not during the analysis period)—medium (Mw ~ 6.5)Moderate (b ~ 1.0)
Hyuga-nada×〇 Medium (Mw ~ 6.7)Moderate to low (b ~ 0.8)
  1. The magnitude size of the SSEs is based on the following studies: (1) Kii Channel (Kobayashi 2014; Geospatial Information Authority of Japan 2016); (2) west to central Shikoku (Takagi et al. 2016); (3) Bungo Channel (Ozawa et al. 2013; Ozawa 2017); (4) northern Miyazaki (Ozawa et al. 2001); and (5) Hyuga-nada regions (Yarai and Ozawa 2013)