Fig. 3.

(a) Epicenters of earthquakes used in this study (1 January, 1996–31 December, 2007, M ≥ 3.9, 0 ≤ Depth (km) ≤ 90). This earthquake catalog includes clustered events such as aftershocks and earthquake swarms. (b) Space-time plot of earthquakes shown in (a). (c) Temporal change in b-value and M_c in the entire study area. Mc is the minimum magnitude that satisfies the G-R relation. The time window is two years long. For example, a value plotted for 1997 is calculated from earthquakes between 1996 and 1998. (d) Cumulative number of earthquakes as a function of time. Magnitude labels on each curve indicate the lower threshold of magnitude. For example, the curve with a label of M 4.0 represents the cumulative number of earthquakes with M ≥ 4.0.