Fig. 5

Cumulative number of shallow earthquakes. Panels are a with M_S ≥ 7 globally, b with M_JMA ≥ 6 in the regional area around Japan (1885–1980) based on Utsu’s catalog, c with Ms ≥ 7 in low latitude areas, |θ | ≤ 20^o, of the world (1897–1980), and d Ms ≥ 7 in high latitude areas, |θ | > 20^o, of the world (1897–1980), where θ is the latitude