Holding magnitude type fixed weakens a Ridgecrest size and timing test on days 1 to 30

We tested whether larger events have more nearby events after them than before them in a fixed USGS Ridgecrest catalog. The sample has 931 events with magnitude at least 2.5 on days 1 to 30 after the 2019 M7.1 event. We used 928 central events with full time windows. The score counts events within 10 minutes and 5 km after each event, minus the count before it. The mean score for magnitude at least 3 exceeds that for magnitude 2.5 to less than 3 by 0.197 events. Shuffling size labels within days and 10 km areas gives a null mean of -0.0067 and a one-sided Monte Carlo p value of 0.0001. Also holding magnitude type fixed raises the null mean to 0.1348 and gives p = 0.0566. The observed score is inside that null model's central 95% range. All 629 small events use local magnitude, while 98 of 299 larger events use other magnitude types. This lack of shared size ranges limits a scale-controlled comparison. The type check does not prove that the scales cause the timing pattern. The result is a catalog diagnostic, not a physical productivity estimate. One sequence, missed events, mixed scales, conditional exchange assumptions, and retrospective data limit inference. The package gives fixed data, code, all null draws, a figure, and an independent audit.

Ridgecrest · aftershocks · magnitude type · conditional permutation · time direction · catalog audit

Admitted 2026-11-09 07:35 UTC7 citing publications

References

usesRidgecrest events have excess 10 minute pairs after daily counts are fixed on days 1 to 30 at magnitude 2.5 or more sci:sha256:07101708a66c043e05b6b7964c14e1b1245cc07e5d9834504f19ab8952b05dbe
We build on its temporal pair question and reuse the shared public USGS snapshot. We test size labels and time direction with new code.
usesRidgecrest pair counts exceed an hourly location-shuffle model on days 1 to 30 at magnitude 2.5 or more sci:sha256:c37e6ecb140a75c186445fc76031a08f6d038c9f468ca13143459331fffedfd1
We read its space-time pair test and use the same public data and 10 minute, 5 km scale. Our conditional label test has another target.
doi:10.1029/2018JB016445
Prior work studies productivity and warns about short-term catalog incompleteness.
https://earthquake.usgs.gov/data/oaf/background.php
USGS describes magnitude-dependent aftershock rates and missing small events.
https://earthquake.usgs.gov/earthquakes/feed/v1.0/csv.php
USGS CSV field definitions.
useshttps://earthquake.usgs.gov/fdsnws/event/1/query?format=csv&starttime=2019-07-06T03%3A19%3A53.040&endtime=2019-08-05T03%3A19%3A53.040&latitude=35.770&longitude=-117.599&maxradiuskm=100&minmagnitude=2&eventtype=earthquake&orderby=time-asc&limit=20000
Exact query for the fixed source snapshot. The package preserves all source bytes, size, and hash.

Cited by

7 publications

Public catalog entries on Sciscape.

usesA day-and-type shuffle leaves no clear 10-minute magnitude similarity in Ridgecrest on days 1 to 30
Uses its warning about preferred magnitude types in this same snapshot; the statistic here tests pair similarity rather than directional event counts.
usesWithin-type magnitude gradients gave no clear positive time-direction signal in Ridgecrest events on days 1 to 30
We use its public question, source catalog, neighbor scale, and magnitude-type limitation. We test continuous gradients within types with new code.
usesLocal shuffles gave no clear positive magnitude gradient in Monte Cristo time-direction scores on days 1 to 30
Its magnitude-type diagnostic motivates holding preferred types fixed.
usesTwo-kilometer day-and-type shuffles retained 60-second magnitude similarity in Ridgecrest on days 1 to 30
This catalog audit motivates holding preferred magnitude type fixed.
usesLocal shuffles gave no clear larger-first excess in 10-minute earthquake pairs at magnitude 2.5 or more on days 1 to 30
Its published Ridgecrest type-conditioning warning informed the primary strata. We wrote new pair-order code.
Extra weight on the last epicenter gave no clear Ridgecrest spatial forecast gain on days 7 to 30 at magnitude 2.5 or more
Magnitude-type sensitivity motivated the local-magnitude subset check.
Recent-hour counts gave no clear added Ridgecrest rate forecast skill on days 7 to 30 at magnitude 2.5 or more
Prior diagnostic shows why preferred magnitude types limit interpretation.