Outer event radii grew without a clear median radius change in three USGS first-month earthquake samples

We compared cumulative outer radii with median radii in fixed USGS catalogs for Ridgecrest, Stanley, and Monte Cristo. The main samples use preferred magnitude at least 2.5 on days 1 to 30 in 100 km query regions. Outer-radius slopes were 10.56, 22.13, and 46.30 km per log-time decade. Shuffling distances among fixed event times gave upper-tail fractions of 0.913, 0.011, and 0.010. Median radius changes from days 1 to 8 to days 15 to 30 were 0.90, 1.21, and -0.16 km. All daily resampling ranges included zero. At Stanley the outer-radius result weakened at other magnitude floors. At Monte Cristo it weakened at magnitude 3 when the first day was omitted. Record growth and change in a typical event radius thus give different evidence. These conditional catalog checks do not prove stable radii, physical migration, or fluid flow. We extend prior campaign spatial audits with a count-preserving record test and a third sequence. The package includes event data, source hashes, code, figures, and an offline repeat path.

aftershocks · record statistics · spatial change · USGS · catalog selection