Earthquake Clustering and Energy Release of the African–Arabian Rift System

Abstract

The earthquakes associated with continental deformation are spatially and temporally variable and are fundamental in understanding fault activity and seismogenic hazards. We conduct K-means cluster analysis on seismicity in the AfricanArabian rift systems to create the first computationally objective analysis of the pattern of earthquakes. We use seismic moment to compute spatial variations in maximum credible earthquake (Mcred) and likely time to the next major release of seismic energy. Our best-fit model has 32 clusters of ∼100-400 km in length, with cluster size decreasing northward along the rift and cluster boundaries correlating with major structural segmentation of the rift. Mcred varies between M w 5.2 and 7.4 across the whole dataset, with the highest values estimated in portions of the rift where the majority of extension is accommodated by seismogenic failure.

Spatial-temporal Distribution Characteristics of Global Seismic Clusters and Associated Spatial Factors

“…The seismic energy in each grid is the total energy of the earthquakes located in the grid. Itis calculated according to seismic magnitude (Hanks and Kanamori, 1979;Hall et al, 2018). The relationship is shown in Equation ( 4…”

“…The clusters are heterogeneous in terms of spatial-temporal distribution. From a spatial perspective, cluster size in the African-Arabian rift decreases northward (Hall et al, 2018), and clustering of large earthquakes is evident along the Sumatra, Kuril, and Tonga subduction zones (Lay, 2015). From a temporal perspective, earthquakes are more likely to cluster around a large one (Kagan and Jackson, 2000;Jiang and Wu, 2005).…”

“…However, the indexes still cannot perfectly assess seismicity (Mulargia et al, 2017). Clusters could be distinguished in the temporal evolution of seismicity (Hall et al, 2018;Wang et al, 2018). Then their characteristic would reflect seismic activity.…”