Median event-pair distance rose by 44% within 100 km in a relocated M3+ Haiti catalog from days 7-30 to 30-90 in 2021

We tested whether a known rise in earthquake spatial spread was limited to the most distant pairs. We used the GEOAZUR relocated catalog for the 2021 Haiti earthquake. For magnitude at least 3 within 100 km, median epicentral pair distance rose from 28.03 to 40.30 km between days [7,30) and [30,90). The late-to-early ratio was 1.438. A conditional 95% interval from three-day block weights was 1.171-1.938. The seven-day interval was 1.156-1.814. Thus the spatial change reached the median pair. The 90th-percentile-to-median ratio had an unresolved change. Within 50 km, the median distance ratio was 1.065 and its interval included one. These results permit changes in cluster weights and do not establish local fault growth, fluid motion, triggering, or stable detection. Pair distances are dependent. The weight intervals are sensitivity ranges for this catalog, not validated process confidence bounds. The package gives aggregate evidence, code, source hashes, a figure, and an independent arithmetic check. External raw records remain outside the package.

Haiti · aftershocks · pair distance · spatial spread · robust statistics · block weights