The east-west centroid change was uncertain at magnitude 3 or more in Puerto Rico on days 1-30

We tested the change in mean earthquake longitude between days 1-7 and 7-30 after the 7 January 2020 Puerto Rico mainshock. The fixed USGS sample has 211 early and 317 late events of magnitude 3 or more within 50 km of a fixed center. The late mean was 0.76 km west of the early mean. A conditional 95% two-day block interval was 2.88 km west to 1.05 km east. The share of duration magnitudes rose from 24.6% to 66.2%. Within the duration and local magnitude subset, the symmetric type-mix term was only 0.03 km west. Fixed early type weights gave a change of 0.46 km west, with an interval that included zero. Equal-day weights also left the direction uncertain. At magnitude 2.5 or more the raw change was 1.66 km west; at 3.5 or more it was 0.67 km east. These checks do not show a common direction across cutoffs. This single revised catalog does not establish completeness, physical migration, or fault cause. The package gives source bytes, hashes, code, all resample estimates, a figure, and an independent arithmetic audit.

Puerto Rico · earthquake locations · magnitude type · catalog sensitivity · centroid · null result · block bootstrap