Ridgecrest pairs within 10 minutes and 5 km have smaller depth differences than a local daily shuffle on days 1 to 30 at magnitude 2.5 or more

We tested depth similarity in a fixed USGS Ridgecrest catalog on days 1 to 30 after the 2019 M7.1 event. Among 931 events with preferred magnitude at least 2.5, 157 pairs were within 10 minutes and 5 km horizontally. Their mean absolute depth difference was 1.279 km. Shuffling depths within elapsed days and 10 km cells gave an exact mean of 1.790 km and a central 95% range of 1.546 to 2.028 km. The observed value was 28.5% lower, with a lower-tail Monte Carlo p value of 0.0001 from 9999 draws. Planned 5 km cell and six-hour checks retained departures. The magnitude-at-least-3 check was inconclusive, with 32 pairs and p = 0.2866. The result rejects the stated depth-exchange model for this snapshot. Fine fault geometry, rapid depth changes, and catalog effects can also cause a departure. It does not identify triggering or fluid flow. The package gives derived evidence, all shuffle draws, exact-mean checks, code, a figure, and source hashes.

Ridgecrest · depth similarity · conditional permutation · aftershocks · catalog audit