A correlation between the b-value and the fractal dimension from the aftershock sequence of the 1999 Chi-Chi, Taiwan, earthquake

We analyse large number of aftershock events from the 1999 Chi-Chi, Taiwan, earthquake (M_L 7.3) recorded around the epicentre area of the main shock in central Taiwan where events can be precisely located, due to dense coverage of modern seismometers. The seismicity is characterized by the b-value of the Gutenberg-Richter relation and the fractal (correlation) dimension D of earthquake hypocenters calculated from sliding windows containing more than 100 events. Over a span of 6 months after the main shock, we find a positive correlation between b and D from the aftershock sequence. Our result thus suggests that Aki's relation D = 3b/c could be possibly applied to one single fracturing process and its related aftermath.