a, Fraction of links longer than 2,500 km (blue) and median of the link-distance distribution (orange) for different event percentile thresholds. Both quantities remain similar over the range of thresholds, with slight increases towards the strongest events. b, d, f, h, The corresponding distance distributions are shown for the 80th (b), 85th (d), 90th (f) and 95th (h) percentiles for comparison. c, e, g, i, Significant link bundles attached to SCA are also shown for events above the 80th (c), 85th (e), 90th (g) and 95th (i) percentiles. Links shorter (longer) than 2,500 km are shown in red (blue). A spherical Gaussian KDE of the regional link density, in combination with a null model of randomly distributed links, is used to determine link bundles; links that are not part of significant bundles are omitted (Methods section ‘Significance of spatial patterns’). Significant link bundles are shown by blue contours in units of standard deviations above the mean. The mean and the standard deviation are inferred from the null model of the regional link density. The black contour line delineates areas in which the regional link density is higher than the 99.9th percentile of the null-model distribution.