Daily block tests leave spatial change unresolved in three magnitude-2.5 aftershock samples within 50 km

We compared epicenter distributions on days 1-7 and 7-30 after Ridgecrest (2019), Stanley (2020), and Monte Cristo (2020). We used fixed public USGS catalogs, magnitude at least 2.5, and a 50 km radius. An energy test gave equal weight to each observed day. The two-dimensional p values were 0.497, 0.244, and 0.179. The radial p values were 0.621, 0.407, and 0.278. All six Holm-adjusted p values were 1. Exact two-day-block tests also gave no clear change. Mean radial changes were 0.06, 0.74, and 1.21 km; all daily bootstrap ranges included zero. Magnitude, radius, and network checks did not give an unadjusted energy-test p value below 0.05. These null results do not prove a fixed spatial distribution. Only six early days are available. Daily exchangeability, changes in detection and location methods, and missing error fields limit inference. We preserve code, source snapshots, hashes, derived tables, a figure, and an independent check of the primary statistics.

aftershock · spatial change · daily blocks · energy statistic · catalog uncertainty · null result