TY - JOUR ID - epos195 UR - http://dx.doi.org/10.1103/PhysRevLett.101.018501 IS - 1 A1 - Zaliapin, Ilya A1 - Gabrielov, Andrei A1 - Keilis-Borok, Vladimir A1 - Wong, Henry Y1 - 2008/07// N2 - We introduce a statistical methodology for clustering analysis of seismicity in the time-space-energy domain and use it to establish the existence of two statistically distinct populations of earthquakes: clustered and nonclustered. This result can be used, in particular, for nonparametric aftershock identification. The proposed approach expands the analysis of Baiesi and Paczuski [Phys. Rev. E 69, 066106 (2004)] based on the space-time-magnitude nearest-neighbor distance ? between earthquakes. We show that for a homogeneous Poisson marked point field with exponential marks, the distance ? has the Weibull distribution, which bridges our results with classical correlation analysis for point fields. The joint 2D distribution of spatial and temporal components of ? is used to identify the clustered part of a point field. The proposed technique is applied to several seismicity models and to the observed seismicity of southern California. PB - The American Physical Society JF - Physical Review Letters VL - 101 SN - 0031-9007 TI - Clustering Analysis of Seismicity and Aftershock Identification AV - none ER -