Correlations Between the Mainshock and the Largest Aftershock for Taiwan Earthquakes

From the mainshocks of 85 Taiwan earthquakes (M (s) > 5) and their aftershocks reported in the Earthquake Data Report by NEIC PDE catalogue, several correlations between mainshocks and their aftershocks are studied. Results show that the magnitude difference (Delta M (s)) between the mainshock and the largest aftershock slightly increases with the mainshock magnitude (M (s)) and varies from 0.1 to 2.2, with two values of 0.3 and 0.9 having the largest numbers of events. The mean value of Delta M (s) is 0.83 +/- A 0.46. The differences of occurrence time and epicenter between the mainshock and the largest aftershock do not clearly correlate to M (s) as well as Delta M (s). For the whole data set, 36.5 and 77.7% of the largest aftershocks are located near their individual mainshocks within a distance of 10 and 40 km, respectively. The difference in occurrence time somewhat increases as the difference of epicenters increases.