Characteristics of earthquake clustering in and around Japan revealed by single-link cluster analysis

In this study, we apply the single-link cluster (SLC) method to analyze the characteristics of earthquake clustering in Japan. Among the clustering algorithms, the SLC method is effective in characterizing earthquake clusters or isolated events at both global and local scales. The results indicate that link lengths for the whole investigated area in and around Japan follow negative exponential functional or Gamma distribution functional increase. Besides, some difference is revealed among different areas, e.g., link lengths in the area of the Japan Trench and the Kuril Trench are shorter than those in other areas; the densest spatial distribution of the SLC framework is also in the area of the Japan Trench and the Kuril Trench. The close investigations indicate that the α and 1/θ values estimated respectively from the exponential function and Gamma distribution may relate to spatial clustering, which is supported by the results of the distribution of link lengths and the spatial distribution of the SLC framework in the investigated areas.