Research Information System
INTERNATIONAL JOURNAL OF EARTH SCIENCES, vol.110, no.1, pp.253-261, 2021 (SCI-Expanded, Scopus)
This analysis is an extension of the studies based on the space-time-magnitude domain nearest-neighborhood distances (n) obtained from two successive earthquakes. We included epicentral depth as a parameter, and established a new analytical solution for seismicity clustering in the space-time-depth-magnitude domain. The proposed technique was applied to SW Japan seismic observation data for 2011-2018, and revealed that the temporal, spatial, and epicentral (T, R, E) components of the joint distribution for n were prominently bimodal, indicating the presence of two, statistically distinct, earthquake populations. We used the Lomb-Scargle periodogram (LSP) to generate a power spectrum preceding the Kumamoto earthquake, and detected the periodic component of unequally spaced points for log(10)n (logarithmic scale of n). The LSP showed a dominant peak corresponding to the time period between foreshocks and aftershocks, due to the highest number of recorded n observations. The technique presented in this paper can be applied globally for any time period and any seismotectonic zone preceding large earthquakes of interest.