Table 5 The characteristics of slow earthquake phenomena and regional structure in different areas of Shikoku
ID | Description of characters | A | B | C | D |
|---|---|---|---|---|---|
1 | Equivalent magnitude of long-term SSEs (Hirose et al. 2010; Takagi et al. 2016) | Mw 7.0–7.1 | Mw 6.0–6.3 | Mw 6.0–6.3 | x |
2 | Recurrence interval of short-term SSEs (Hirose et al. 2010) | \(5.6 \pm 1.7 \mathrm{months}\) | \(2.7 \pm 1.4 \,\mathrm{month}\) | \(2.8 \pm 1.6 \,\mathrm{month}\) | |
3 | Slip rate inferred from tremors (Hirose et al. 2010) | \(4.2 \pm 0.6 \mathrm{cm}/\mathrm{yr}\) | \(3.3 \pm 0.4 \,\mathrm{cm}/\mathrm{yr}\) | \(4.9 \pm 0.6 \,\mathrm{cm}/\mathrm{yr}\) | |
4 | Large | Largest | Small | Smallest | |
5 | High | Moderate | Small | Smallest | |
6 | Duration (Fig. 2 of this study) | More long-lasted events | More short-lasted events | ||
7 | Sensitivity to tidal stress (Ide 2010, 2012; Miyazawa et al. 2008) | Lowest | Low | High | High |
8 | 70% eastward (fast in A, slow in B) | 64% westward | 67% eastward | ||
9 | Strength of patches (Kano et al. 2018) | Strong | Moderate | Weak | Weak |
10 | Density of brittle patches (Ohta and Ide 2017) | Dense | Moderate | Sparse | Sparse |
11 | Viscosity of background region (Ohta and Ide 2017) | High | Moderate | Low | Low |
12 | Qp structure above the slab (Kita and Matsubara 2015) | High | Low | High | Low |
13 | Heterogeneity of asperities inferred from NPks_DFTmean and NPks_DFTmed in this study | Small | Large | Large | Small |
14 | Size of tremor zone inferred from duration, \({ACF}_{2/3}\), and \({ACF}_{1/3}\)/\({ACF}_{2/3}\) in this study) | Large | Largest | Smallest | Small |