Earthquake frequency-magnitude distribution and fractal dimension in mainland Southeast Asia

Abstract

The 2004 Sumatra and 2011 Tohoku earthquakes highlighted the need for a more accurate understanding of earthquake characteristics in both regions. In this study, both the a and b values of the frequency-magnitude distribution (FMD) and the fractal dimension (DC) were investigated simultaneously from 13 seismic source zones recognized in mainland Southeast Asia (MLSEA). By using the completeness earthquake dataset, the calculated values of b and DC were found to imply variations in seismotectonic stress. The relationships of DC-b and DC-(a/b) were investigated to categorize the level of earthquake hazards of individual seismic source zones, where the calibration curves illustrate a negative correlation between the DC and b values (Dc = 2.80-1.22b) and a positive correlation between the DC and a/b ratios (Dc = 0.27(a/b)-0.01) with similar regression coefficients (R2 = 0.65 to 0.68) for both regressions. According to the obtained relationships, the Hsenwi-Nanting and Red River fault zones revealed low-stress accumulations. Conversely, the Sumatra-Andaman interplate and intraslab, the Andaman Basin, and the Sumatra fault zone were defined as high-tectonic stress regions that may pose risks of generating large earthquakes in the future.